What I like & what I don't

Oh, thanks, steve. So ok, the tool is already there, but my argument still stands! 
It just made some other thing more prominent: It would have been a lot easier for me to find this tool, if the hierarchy of tools had an additional level, or another kind of hierarchy. Presets would accomplish such a thing, because the list of superordinated tools would be shorter, and then fan out on the preset level. Now I'm just repeating myself.
And yup, at the moment you can perform the tool with the last settings (unsless it's linked to MMB it seems), but with presets I could set up different settings, for example like a chamfer for really round edges (0.5, refine, rounded, 6 segments, offset 0) and a chamfer for smaller geometry (0.03, refine, rounded, 1 segment, Offest 1).

As you guys surely have noticed by now, I'm pretty hardheaded on that tool preset idea to the point where I'd like that spark of an idea to become a full blown plasma torch that burns into the very foundation of the program, more or less. As I was further thinking about it, I imagined what the marketing ads would look like for NVil with it's current system.
"Choose from hundreds of developer predefined tools for your customization!" Well, less is the new more. Instead it could say "Save any personalized setting of a basic tool as a preset and bind it to a hotkey, user button or radial menu for easy access. NVil already comes with the most common presets ready to use." And then something splashy between the lines of "This is my rifle. There are many others like it, but this one is mine."

Don't get me wrong, there' a lot I like about NVil, but the long lists of tools and how they're ordered and cluttered is something only a mother could love. I did start a list with all the tools to work on suggestions how to declutter and consolidate them, but new tools keep coming in, so I probably have to start over.

Since this could mean, that people may have to do their setups again, maybe save it for a major release. OR do it as fast as possible, so less paying customers would have to go through with it!

It just made some other thing more prominent: It would have been a lot easier for me to find this tool, if the hierarchy of tools had an additional level, or another kind of hierarchy. Presets would accomplish such a thing, because the list of superordinated tools would be shorter, and then fan out on the preset level. Now I'm just repeating myself.

Why would a list of tool presets(settings) be shorter than the list of tools that give those presets?

And yup, at the moment you can perform the tool with the last settings (unsless it's linked to MMB it seems),

MMB action is stored and repeatable (in current session) on my setup.

but with presets I could set up different settings, for example like a chamfer for really round edges (0.5, refine, rounded, 6 segments, offset 0) and a chamfer for smaller geometry (0.03, refine, rounded, 1 segment, Offest 1).

I have not yet found a need for tool presets. All the models I build are different and therefore are different in the tool settings that are required to create the model.

Why would a list of tool presets(settings) be shorter than the list of tools that give those presets?

It wouldn't be one big list on the streamline basic tools level anymore. As I stated, it would be one list with superordinated tools, like Extrude, Chamfer, Cut, Split and so on, and the different manifestations like extrude_cursordirection, extrude_polynormal_individual, local_move_average, last_used_setting, default, show_options etc. would be listed in a dropdown besides the tool. Thus, the list on level 1 you are presented with gets shorter. I could also save a setting, that would make 'by individual polygon' in 'polygon grouping options' of the extrude tool the preferred method of extruding, without the need of pressing space before extruding (but the other way around). It would be up to you.
It could well be that you wouldn't even need the distinction between 2 lists, the tools and the streamline basic tools, anymore. You'd just have the tools list, where each entry, that supports presets, has a dropdown with presets to choose from. The default setting for those tools could be "show options". You could easily change that in the tools list. And when in the streamline tools editor, when choosing a tool for LMB drag, for example, you again get the tools list and select a tool with the wanted preset.
You wouldn't be constrained to just basic streamline tools, you could also set up presets for commands like delete(options), split, duplicate, FlipXYZ, Subdivion, Instance etc.

But you would still need presets for each individual function, so the list of presets would still be the same number as the functions (if one preset per function).
For example:- You mentioned

and the different manifestations like extrude_cursordirection, extrude_polynormal_individual, local_move_average,

Those can be placed in one streamline engine tool, but they are different functions with different possible results, so each would require different presets.
If you did not have different presets for each individual basic streamline tools, how could you build streamline engine tools in the way you put forward?
To me it looks more like making the basic streamline tools into visual tools, with full options shown in drop_down with preset entries. One of the main aims of the streamline engine tools is to avoid that for quick workflow.

But you would still need presets for each individual function, so the list of presets would still be the same number as the functions (if one preset per function).
If you did not have different presets for each individual basic streamline tools, how could you build streamline engine tools in the way you put forward?

I feel like I need to clarify a few things about my suggestion. When I say "tool", I mean the tools that you have, if you go to 'Edit->Customize->Tools'. In the current state, there are a lot of tools that display some kind of options, like 'Delete(Options)', Extrude(Polygon Shortcut Tools). If I assign a hotkey to such operations in the tools customization, it will open up the options window for that tool.

A streamline basic tool is nothing else than a preset made for a visual tool by the developer. When I said "manifestation" I did mean the streamline basic tool, because it is a visual tool that manifests itself in a specific bahavior without opening the options.
What I would add, is the ability to setup and save such streamline basic tools yourself, by adding preset management functionality to EVERY option window where you can choose between different settings, not just for visual tools, but including delete, flipXYZ and split for example.
Since streamline basic tools are subordinated manifestations/presets of a visual tool, I could as well order them in that way, resulting in an additional level of hierarchy. So I would have a list containing these tools: bridge, extrude, chamfer, tweak ... Now imagine that each of these tools has a dropdown menu besides its name, where the streamline basic tools for that specific tool are listed (Poly-Extrude: CursorControl_GroupTogether, IndividualDirections_byIndividualPolygon, IndividualDirections_GroupTogether etc.). In addtion to the user/predefined presets, I would add a default bahavior (kind of default streamline basic tool) and "show options" (which would be the visual tool as it is now), as well as "last used" (last used configuration of that tool as a streamline tool) to the dropdown menu.
I could now go into "Edit->Customization->Tools", look for a tool like extrude and change it's dropdown from default to CursorControl_GroupTogether preset. If I pressed this hotkey I would enter the streamline basic tool, but still be able to call the options with the home key, or cycle through the presets by pressing the option cycler key (which would also change the settings of "last used").

Besides the normal hotkeys, I would still have the streamline engine tools setup. But when clicking on "set" of the LMB Tool I would get kind of the same list with bridge, extrude, chamfer, ... but they'd too have the dropdown besides their name from which I choose a specific preset. So I can set "Poly-Extrude: CursorControl_GroupTogether" to LMB and "Poly-Extrude: IndividualDirections_GroupTogether" to RMB, just like it is possible now. Only the look of the UI has changed, and I can setup my streamline basic tools myself, if I want to. So yeah, the number of TOTAL presets can be way higher, than the current number of streamline basic tools, but it'll be more well arranged, because they'd not be listed one after another in a huge list but by their superordinated tools (extrude, bridge, chamfer,... each with their presets ordered in a dropdown beside the name).
Of course, NVil would have a number of predefined presets per tool, just like it has now with the streamline basic tools.

In the current state of NVil, you could arrange the UI in the same way I described, because streamline basic tools are those presets/manifestations I am talking about.

I hope there are now no more misconceptions about my suggestion. Next time, I will mash up pictures of the UI as I imagine it. Or maybe I will do anyways, just in case.

+ I find, the new organization in tree views and expandable categories makes the lists of tools much less intimidating. It gives me a better overview of what's what.

+ Retopo tool has some nice features. Being able to move/extrude whole loops by just clicking one egde, striping, creating a polygon from extruding a vertex, bridging multiple edges, rotating and scaling, the improved rendering to better see the mesh.

I don't know if it was mentioned here already in this topic, but what I just love are the: Turn Flow and Turn Flow and Relax commands. They're so freakin' cool! They completely eliminate the necessity of using spin edges commands and guessing what edge to spin in order to reroute the geometry flow the way I want it to go. IStonia, you're the best, man.

+ Some parts of the whole presets idea I had, are now possible with the composite tool editor. This is great, even though I think this feature is just getting started.

+ The tool search inside the tools editor/window is a huge time saver. I now especially noticed it while playing with composite tools, where I search for a lot of tools in quick succession.

+ Edit >> Preferences >> Special Options >> "User Settings" folder in application folder
That allows me to start NVil with different setups (e.g. one default for making wiki-screenshots)

+ constant development

+ I just realized how important the feature of combined keyboard & mouse shortcuts is for NVil. I think no other application does that and it's totally useful. Press a hotkey + mousebutton, simple but very effective.

+ "tapped" key state to call some function. So I can have the visual tool on tapped and the streamline tool on hold. Still, release state slots in streamline tools would be nice, too.