All the maps you listed at the end are good maps, they just don't get their share of votes >.< Fortress Pyke is great, Kharmunrah is at least decent (though all the lava in one area is annoying and how I can never seem to find a tier 2), Fallen Empire is a great map other than it's massive size and Treacherous Heights is also pretty good.
Of the PMC maps, I hate Destiny's Shiver, I haven't played much Fallen Colossi and I quite like Avaricia. It also seems to be popular in the community, I've been playing on that map a lot.
Anyways, the map committee, like said above, is just there to improve the map selection system. I think it was explained pretty well above
