I real life, tanks have a driver, a gunner, a commander, plus other crewmembers depending on how advanced the tank is (loader if you don't have an autoloader; radio operator if it's too complicated or primitive to be operated by the commander; extra gunners for those hull MGs/AA MGs/secondary turrets; etc.)
In the world of FH2/BF2, one man or woman can fully operate the tank, an extra person is required only for firing guns from different crew stations simultaneously. Plus you can swap positions instantly which is certainly not possible in real life, plus you cannot drive from the driver's position with the exception of Marder III...
IMHO, the suggestion for crewmembers killed separately, depending on the point of impact of a penetrating shell, would be worth the effort only if a tank really required a certain amount of crewmembers to function, or at the very least that its performance would be dependent on the number of crew members in the inside slots. As this is not the case, the "damage counter" and eventual burning will suffice.