A change in Map playlist is really in order really. Adding new layers/etc to counteract the bad taste of a map that is way past its due-by-date is not a fix at all.
New and fresh Maps/Environments are an important part of the lifeblood of a game and AH is maybe lacking that at the moment, so they probably keep things *fresh* by making people play boring maps to provide some sort of perceptive contrast with the ones that still remain some level of refined enjoyment.
Mind you, with the current situation; this lack of good maps is more of the communities fault, since the tools are out there to make the new maps and it no longer lies on HTC's laurels to give the community what it think its needs it that concern.
From my own experience, It feels to me like the enthusiasm for having a good map quickly decides its fate in the current environment, whereas maps which bore people don't generally finish quick enough due to the lack of desire to even play on it, let alone surmount the required effort to finish them.
Anyone would like to guess the average lifespan of a map in AH? One, maybe two years?