So far we can only select up to 2,3,4,8,16 players to play in a map, and we never got to be able to type in a number that we wanted. I mean, what if we got a map that only supports 6 , 12 or 14 players only? If we set that to 8/16 players then the 'void' slots will give the players an error when they try to connect. Hence I think it is really needed to us to input a number for the number of player-slot instead of having a selecting option.
(Or maybe have a option of 2~16 is also fine.)