Some people may not like the custom forged maps 343(correct me if i'm wrong) implemented into the game in Reach. I respect their opinions. I think that custom forged maps in MM are a very good idea.
There are a total of 5 4v4 infinity slayer maps. One of the 5, Complex, is hardly even played thanks to the DMR. This game has only been out for almost 2 months and I am already bored of the infinity slayer maps. I liked what they did in Reach to give a variety to the multiplayer maps. It also let talented forges show off their maps to the whole Halo community.
What I am saying is for 343 to let players submit their maps in to 343 to be implemented into the game. They could even have a weekly rotation for the maps.