the community for 4v4 community maps is like this:
You have top teams that want a balance of cover, with not to much green do to how it blocks projectiles, and they are going to want a spread of engagement lengths spread across the map. You will also have to be wary of how the map paths and resource layout will need to be placed in a way where cutoffs can be punished and is fair for both sides.
You will also have to be wary of bofors/mortarpit/okw truck. And typically "domination buildings" are a very large no go.
For community maps with the most play and most downloads... you just put 1-2 chokes on the entire map and let people stomp AI. Balance won't really matter here as long as the map has lots of explosions.
+1