by Tomasz Muras.
re-inventing the wheel for each plugin makes no sense and also using a framework cuts down on maintenance and standardizes the plugin so another developer can contribute more easily
I have a very similar experience, each plugin contains a lot of of boilerplate code that could be extracted and managed under some kind of common framework. I would create a framework like this but I gave up on the idea of doing it by myself - I think it's pointless if not agreed by wider community, especially Moodle HQ. This is the reason that I've instead implemented generating templates of the code in moosh.
If I were to do it all over again today, I would try to make use of Symfony2 components.
I would do the same, Drupal 8 made similar decision.
cheers,
Tomek