I'd stick to improving existing OS packages, and let "useful" stuff stay in Extras. If the community wants to get involved in endorsing other nice things (like, oh, I dunno, fMMS or similar), that sounds like a separate project to me.
Ditto for FOSS replacements of closed Maemo apps. Or, IOW, I wouldn't mind having the ability to, say, uninstall Modest (since I never use it), but I don't want that sort of silly side preference to hold up getting other bugfixes going quickly.
Depends: ..., mediaplayer (= 1.3-4+0m5), ...