Why not implement a limit on the number of vehicle types per game ? as with the bombers, which can only have 4, the same applies to the rest of the aircraft ?
Most of the games from 9.3 onwards are practically all the same. Most of them only use Atackers due to their great capacity to carry bombs.
There is also another problem and that is the amount of bases to destroy in most of the maps are 4 and in some cases take quite a long time to regenerate, if the amount of the same and the amount of bombs to destroy them would be much better experience in the game.