Seems like a good idea to me.

Not sure how this would work. The only thing I can see this indicating is the popularity of the map, which can already be determined by the existing visible stats on submissions. I don't see a way that we could feasibly get a count of how many people are currently playing a particular map on which servers...

Or are you referring to something like "this map is for 1-4 players" so people can determine if something is meant to be played with friends or if it's a single player experience...?