Well, it’s easy enough to keep KB attractive when it mainly consists of Krita’s own dockers 
A lot of good reading in this topic even with such few posts! I feel like I can weigh in on this a little:
To an extent, yes. At least if you install plugins manually.
I would definitely encourage people to make the Plugin Importer the default way to install a plugin. The Plugin Importer is very straightforward to use, and plugin developers definitely should take advantage of something that makes installation as convenient as possible for the end user. But I don’t think I ever found documentation on how to create a .zip archive compatible with the plugin importer, which is concerning. Thankfully it was easy enough to guess for me, but it might not be to everyone.
But the fact that it requires not one but two restarts to get a plugin going is rather tedious. Kinda reminds me of the good old days of having to input multiple cd-roms to install a software 
if it would be possible to load in plugins without restarting Krita altogether I would have no complaints whatsoever. I kinda wish plugins were activated by default in Krita, but I take it they aren’t for security reasons?
“Using plugins is not really attractive; apart from the installation process”
This is currently a bit of a non-issue if you ask me. I agree that the wording “Tools” could be better since tools typically already refers to the ones in the toolbox. Perhaps “Utilities” would be better here, if the menu is to house both Macros and Plugins. That being said, if there’s only one entry in a menu then that entry should be the menu. Until the Macros feature get fixed it’s worth renaming the entire menu to ‘Plugins’ or ‘Scripts’. But it’s a very minor improvement of UX if you ask me.
Sub-menus are a good idea, but chance are they’ll be completely foregone by new people testing the waters, and plugins might fit multiple categories, or none. I’m honestly not sure what the best way to do this would be. What I’m personally missing atm is a convenient way to add new sub-menus where you can organize your own scripts and their respective settings. It’s possible, but it’s very cumbersome digging through all the child widgets/menus/actions in the main window just to be able to add a sub-menu under Tools->Scripts(unless I’m misunderstanding something about how this aspect of Qt works).
Scripts are supposed set which pre-existing menu they are added to, but they can’t create a new (sub-)menu. That has to be done via the main window and PyQt5.
“Plugins proposed by default are, sorry, not really attractive”
Also a bit of a non-issue imo. It’s clear to me that most of them were made as small showcases of the API, but they also have good use cases. Could the Ten Scripts dialog look snazzier? Absolutely. Does it have to? Not really, it’s very easy to use and performs well (to the best of my knowledge).
“It’s currently very hard for a new comer to understand how to create a plugin”
Is it though? I can agree the process of setting up a new plugin (creating the appropriate .dekstop file, init.py, the main plugin class, folder structure) is a bit lengthy, but if you have a bit of experience with Python then it’s nothing out of the ordinary. And you probably do want a bit of prior experience with Python. It all makes even more sense when you have some understanding of the different components and systems in Qt. Each part of the set up has a very reasonable purpose. Like @EyeOdin said, the “holy trinity” of Python, (Py)Qt5, and LibKis. 
knowing Qt especially opens up a lot of doors in plugin development!
But a good improvement would be to include a download link to a blank/template plugin somewhere in the documentation just to help people get going. Btw what is this “Python Script Starter” people are talking about?? 
“PyKrita API has a good base, but there’s too much thing that don’t work or that don’t work as expected”
That’s why it’s so fantastic we’re finally seeing people putting the API to the test, discovering problems, and reporting them to the devs (and possibly help patch them as well 
). And as for missing features, I wonder if there’s a wishlist for new features to be added to the API somewhere. I have a couple of entrys to add to that list for sure 
.