If you can't get an injury via fouling someone, then that is a flaw in the programming, and should be changed, considering that in real life people can definitely get injured whilst fouling someone else.
There are many other instances where you can get injured in real life and not in BB. I would not call that a flaw, it is simply the current game design. Basically, any improvement to injuries should probably involve introducing (stamina-related) random injuries. Overall I think injuries should happen during games only, although that is not realistic either, because most people will/can not log in before each game to check for injuries their players suffered in the privacy of their bedroom or in the arena parking lot.