GV's weren't put in the game to serve as targets for those lacking the skills to achieve A2A kills. If you want to bomb, HTC has already provided numerous targets for that purpose.
Gv's are not special or immune from bombs or being strafed. The biggest threat German tanks faced were not other tanks but aircraft, that's why the Germans were forced to travel at night. And I don't think the lankstuka is right either, but being bombed is one of the problems GVs face.