Ok, I'm not disagreeing with you. Some maps are stupidly overpowered in the humans favor yes. But some players enjoy some of these maps, again personal opinion.
Only a few maps would ever be played. And I'm pretty most people like the camping maps for some reason???? No support.
I mean any map zombies will be AFK doesn't matter the map. Also, when you say unbalanced, do you mean that humans always win? If that's the case, it won't really matter if there was vote map because like I mentioned, you will be able to vote for a map once then another map with the highest votes get chosen. Also, majority of the time humans win so I think it'd be fair if zombies got to win. Like I mentioned, you would not be able to vote for a second time. Once it's chosen, and the round is over, you will not be able to choose the the same map. Obviously people like the camping maps, but what I said should answer this. Just cause players like those maps doesn't mean zombies will.