It's true the Registry was not much stable i nthe first place.
But some people did work on it and it's better now.
If you use your own resources/bundles for your addon, there shouldn't be a problem.
With the later added merge option, which BTW works like the merging in the old registry, you can merge your resources into one of the two default bundles Plone comes with. The TTW story still feels not stable and proably never will be. The only except i would make here is, the less compiling TTW. I like this to stay.
But for the rest, we could reduce step by step the complexity as @thet suggested. Bundles are not really needed for your addon. But this is not the big pain point.
What i would like to have changed, is the varibles for the CSS/LESS.
This still seems not working well or at least is confusing for many people.
So either not support it at all or fix it by providing a simple server side rendert LESS file, which provides the needed LESS variables. So that everyone can change some colors of the default theme of plone.
@tmassman did some interesting work too for this kind of persons with his customizeable theme.
All the javascript stuff should be bundled and compiled outside of Plone, with some tool like Webbpack or what so ever. For addons one can use what ever she wants and in core we define a standard but without this tide integration and the requirement of starting a Plone instance to compile the resources.
@hvelarde it is good to point out problems, but please keep in mind, we all have limit time and different needs and therefor different priorities. If someone like @thet steps in and spends a lot of his time to improve the current situation for all of us, it's not nice to rant like this. Many of your points are valid and many of us thing the same. But someone has to do the work. And this is the kind of work, where you get no direct project money for. And some of your points in the plip are already possible. For the rest lets open issues and fix them. I don't see a team somewhere who is defining a complete new solution for that, we have to evolve here the current one step by step.
So let's calm down a bit work together.