lol banning for camping. Might as well ban for strafejumping.
But it's true that's a design flaw that could be fixed in fun ways, for example 10x gaunt power to infected (so they can help each other get to camp spots) or modify fatalinstinct and the overlord modification (the 2 "official" maps and adding one more map to the game isn't that bad in bandwidth) so they have teleports to the top of the map. Or jetpacks, etc.
Also it is kinda boring playing as the survivors; the times I played it I let myself killed so I could play as an infected lol. What can be done is granting powerups to them so it is rewarding to kill and not just to run, for example 10 seconds of quad damage if you kill 5 infected in a round or something.
Zombies with Jetpacks would be nice :)