Cool Anthony . A great question.
You know my efforts to get a few (IMO) basic functionalities into Moodle core over the years - my first e-mail to you was over four years ago I believe. In many cases (most cases), no joy, and the official word from MoodleHQ is plugins is the way to go, and the new plugins database, and the option to install without server access. (BRING IT ON!!)
This I can live with. I now will very rarely work with a Moodle hosting provider who does not offer the chance to install plugins for a reasonable cost. My preference is like the R-L approach here: http://www.remote-learner.co.uk/content/approved-moodle-modules-and-plugins like a whitelist. Took me a while to find some providers who were proactive in this respect.
We choose plugins with care. Is there likely to be a LONG wait for an upgrade to a new version of Moodle? Are they likely to go bust? Are they likely to remove functionality (which has happened) or ignore minor bugs? Do they answer questions? Are they well designed?
Plugin communuication is spread across many areas: docs, forums, tracker and plugin database, blogs, GIT, PM, email. If I have some level or responsibility for a site with plugins then I want to know everything that is going on. So along comes a channel I cannot monitor (the plugins database). Very frustrating. I ask a question, how do I know if there is an answer? Someone else asks a question I know the answer to - How do I know? Comment from the maintainer - how do I know?
A few other items:
Comments threaded view? I can handle NOT having threaded views.
No WYSIWYG or image insertion. Would be better with this.
Reviews. Not really worried about this at the moment. The discussion around this is unfinished. (I asked questions about the purpose of reviews etc and I got a sort of answer about who is trusted to write.) This may be an experiment that failed from my point of view, but it could change.
Documentation. I can live with what is there. No documentation: I will either write some or e-mail the writer of the plugin or something and if no response I just won't bother with the plugin . . . This is almost never an issue, even with comments and notes a bit scattered.
That's just my case. The ecosystem around Plugins then has become important to me. I would like to be able to subscribe to the forums in the plugins database to save having to go back there a lot . . .