While I do think that FFA could benefit from more map diversity, I believe Cam had a valid point it's not all about throwing more maps into the mix, it's also about map rotations and how frequently good ones become available.
We already have a lot of popular flat/open maps such as Tropical, Savannah, Canals, Beach, Kingdom, etc. These players enjoy and tend to have a high activity. So it's not that we don't have good maps perhaps the problem is rotation balance or how frequently less-popular maps appear instead.
Perhaps bettering the map rotation system or allowing players to vote for maps would do more than introducing new ones.