Tank-Ace,
For a guy just starting out and trying GVs, Fireflies, Panthers, Tigers, and soon King Tigers, all must be faced in a M3(75), M8, M4(75), T-34/76 or Panzer IV H. Being at the bottom of the hill skillwise and being relegated to those GVs is a problem. Imagine if new players were limited to Spitfire Mk Vs, Bf109F-4s, FM2s and A6M3s. They'd get pretty frustrated with the Spitfire Mk XVIs, P-51Ds, La-7s, N1K2-Js, Bf109K-4s, Ki-84-Is and Fw190D-9s.
For my part, I prefer to shoot airplanes, but will sometimes offer some bombs if needed. Flak Panzers are fair game at all times.
EDIT:
Tigers are much harder to kill with 500lb bombs than Panzer IVs are. I have hit a Tiger with a 500lb bomb, the other landing ~10-15ft away, and gotten nothing more than an exclamation about how loud it was. I imagine King Tigers will be even harder to kill. 1000lbers probably change that a bit.