It'd be really nice if i could select the size of the map

Originally posted by Flytrap: I dont want the bot number to choose the size for me. I want to change the size independently of how bots im playing against.

That's why we have Creative Mode.

The Perfection gamemode has a leaderboard (and we track your scores in Domination), so we have to keep the settings consistent for all players.

We added Creative Mode so that people could customize their games. You can still play Perfection or Domination in Creative Mode, so it is effectively what you're asking for - the power to play on a map size independent from the number of players.