It has been suggested before, but then it kinda went quiet again. I suggest that we put the random map generator maps into their own matchmaker queues so we got two queues per team size. One with custom maps only and one with map gen maps only for a total of six. This way everyone can choose if they want to play only with or without mapgen or a mix of both by multiqueueing.
It is possible that some queues might see a lot less activity, but firstly I don't think that is very likely and secondly we can monitor this and then think of a way to make the experience better. As a last resort we could remove some queues again if we see that they are totally dead, but I really don't expect this to happen.
Now, before the "I want my setons/dual gap/whatever queue" dudes inevitably show up: This is not comparable. Map gen has been in literally every map pool so far, so we are basically only splitting the pool. No classic map is included in the pool all the time.