But the maps are based off the server, they aren't downloaded to your machine so if they were offered as dlc I don't see how it would work. Now if they were new maps that were added on to servers so that everyone then I'd love that.
If they made a separate playlist for people with map packs, that would work.
Or they could have the game check each player's DLC for the map packs and if any player doesn't have a certain pack, it won't load any of those maps. Would be less awesome for those with the maps, but less trouble for those without.