The problem with adding foilage or any type of detail on tank maps is it starts to make the computer requirment to play them at a decent FPS go up very fast.
On that note. Which one of these is not like the other
http://www.redorchestragame.com/ramm/Orel2_1000m.JPG
http://www.redorchestragame.com/ramm/Orel2_2000m.JPG