The idea sounds good, but a lot of things could go wrong. The standards of the QB should be really high. People don't want to download a billion half-assed, boring maps. Instead it should just be a steady flow of 1 or 2 good maps. Quality should be enforced and maps should be judged heavily. It shouldn't just be checked if there are any major gameplay flaws or if its good looking. They need to be interesting, because even if a map does make it into the base game, if it's not interesting to them, nobody would still play it.
This also means a dedicated testing team. It does not matter if it is a TWI made map or community made map, people loading into a map that is fully integrated into the base game will expect quality. Bugs and balance need to be fully ironed out before they are accepted, because at the end of the day, TWI don't patch often and updating the maps would be a hassle.
As for the whole recooking after every major patch, I really thought that Steam Workshop would have helped solve this problem. Unfortunately, it hasn't and is still broken. I think the idea was that a patch would get released, and the map get updated on SWS, so all the subscribers would get the update shortly after the patch. A lot of the maps there are very outdated and uncooked. I even recall reading about many community map makers not being able to update their maps their at all, essentially rendering the SWS completely useless.