I think one of the problems that you aren't just willing to look at is the presentation to new players.
This is something that Biass and FtX have to watch out for.
Sure the map gen is great addition for us seasoned players who are all sick of BO whoring and want less competitive enviroment where burden of map knowledge is kept to minimum. We can also live with smaller and bigger mistakes like terrain not being obvious or something, as we are getting the kick out of finding new random map to play on. We are fine with ugly decals as long as we don't get to play the same game of burden of knowledge for the first 10 minutes of the game as to how to expand on certain maps or how to not lose the game at minute 11 by having worse Air BO.
But new players won't be as amazed, they will be pissed for having to fight against game again and again where nothing makes sense to them. Them getting a bad map will be much more impactful compared to us. Them seeing ugly map compared to what they can see on current ladder will also look strange. Why are they playing on ugly maps with pathfinding problems when there are hundreds of great hand crafted maps available to them.
Not to mention the fact that with random maps they will never get to feel at home seeing the same map for 3-4 time and now kinda knowing what to play on that map. Instead they will be faced with the daunting experience of having to play against not only enemy but also against brand new map with each new game.
Not to mention the fact that the newbies will have even harder time getting accustomed to setting economy up and running when they have to learn how to improvise BO each and every time they enter the match. What you all want to do is all nice and dandy if you are seasoned player who already have played the game for a while and is accustomed to it's problems.
But a new player? You are literally inviting living hell upon them and making sure that the ladder experience will become even more daunting to many of them as they get scared of yet another layer of unknown.