At vB (yeh yeh I know) they seem to have pretty much decided against this. Could be because of copyright issues, I don't exactly know how that works. On the other hand, some of the addons (including but not limited to: BB code manager, editor manager and Widget manager) are good ideas that in my opinion would improve the core product. Multiple people can always come up with stuff that a single person could not.
So I'm curious, are you going to watch what people come up with and maybe use that? And developers, would you like / dislike it if they use your idea (so just the idea, not the code itself) for the core product?
Not entirely sure if this belongs in the offtopic section, feel free to move it if needed.