> The problem with it is that most of extensions are bad: half-baked, often contradict or duplicate other extensions, and sometimes solve only part of the problem that they intend to solve.

I think that's in the organic nature of protocols catching-up to changing goals and priorities, as the state of the art and the user needs evolve. I think it's pretty-well acknowledged by the XSF (and to a further extent by modernxmpp.org) by curating a short-list of XEPs and behaviours to implement.