Would you trade map bans for longer queues?
Most fun is when you wait for 20 minutes for skyhammer and still play 4×5, because someone went afk…
The amount of effort required to fix the Skyhammer bugs and alter the map to make it a little less cheesy would likely be far less than the amount of effort required to introduce a new map-banning feature.
At any rate longer ques are not what this game needs.