1) Come up with a list of approved match maps.
2) Determine when a map is sufficient to be moved out of beta status.
1. There's so many maps, it'd be restricting if they didn't choose all the maps ppl like to play. I could see this only as a point for leagues or ladders.
2. beta's are in match's and pub's, moving out of beta doesn't effect too much, and besides, this sub-forum is meant to do that right, to help find flaws and what to fix, till its done?
3. Determine the maps that would be included in official DP releases.
this is a good point, I don't think a whole committee would be needed for it though, just a few people watching the pubs and matches, and listing whats mostly played, since its not a big deal if certain maps aren't in there.
Organize a yearly mapping contest?
This is the most feasible reason a committee would be needed, and I wouldn't mind seeing a committee for this, since it would get people interested in mapping. And would help implement good theme ideas in maps.