As I mentioned before in IRC, I think it would be a good idea to let non-devs contribute to the multiplayer maps. Unlike the single player campaign, the multiplayer rotation is just a compilation of unrelated maps, with no clear order and no TUDD that must be followed. When somebody last proposed this, Mystic's response was something along the lines of: "We don't use maps of non-devs because we can't edit them without permission from the author." The solution is simple: Only accept maps of authors who give you permission to do whatever you want with the maps.
The last time I can think of that a map by a non-dev was included was in 1.09.4, with Tree Ring and Isolated Canyon (and maybe some others). Aside from the fact that they're both not very good, I think one of the reasons why Tree Ring was never ported is that the author wasn't around anymore.It's not like popular community maps haven't shown up in the MP rotation before, anyway.