Actually I'm strongly against gimmick maps in map pools because they break my personal principle of a player being able to spawn in with full grasp of game mechanics and being able to iron out a strategy as well as a guy that has 1000 games on the map. Obviously experience has a lot of value and it's impractical to really expect such players to be competitive against one another, but the point is that everything is equal when you enter the game and survey what your options are.
If I had a map that had one random crazyrush mex in the corner, then there's no real reason for you to realize that's a mechanic until it's possibly too late to adjust anything about your build to account for it. Same with the crazyrush map itself. You have no idea if these mexes are infinite, you have no idea if buildings block the script, you might have had no idea that the mexes even expand and blocked it with pgens at the start. It's BS as a player, like if every FAF map had 0 natural reclaim except this one map that is put into a pool every 3rd month.
Of course it is put in tournaments, and that's mostly because people for whatever reason enjoy playing it. I just rationalize it as people knowing the make exists beforehand so it's a fair game since they should be expected to enter the tournament with a knowledge base of the maps in it.
When it comes to map gen, it's the same criteria I had before. It needs to meet the same minimum baseline of quality that I require manual maps to reach.