teahousemoon : As a plugin maker for C2, I can explain somewhat why Ashley isn't integrating what's done by the community (apart from bug report/tests) inside the main C2 product.
First, as SullyTheStrange said, there's legal issues. Since in some of my plugins I'm using open sourced work (in various licenses) to do the job, that implies getting the clearance from all the contributors (some of them aren't on the web anymore, are dead, are in another company, etc...). The legal implications are to deep for a startup like Scirra to enter that mined playing field...
The second problem is that Ashley is already super busy and overwhelmed by the maintenance of his own codebase, his features and all. It's already difficult to keep a whole programming model in his own head when everything is made by you, it's even harder to maintain code made by somebody else. Too much risky...