Now I'm seeing more clear your suggestion. I still don't agree in having a bank account limit but at least I see your point.
The problem is that, tanking, players value decreased by age, the problem of salaries and many other problems of bb are the effect of the -let's say- terrible economic system that the game has. So in order to eradicate the problem you must go to the causes, not to the effect.
All in all, what I mean to say is that having a bank account limit will not modify the causes of the problem. Just the effect. And I also believe that is unnatural... But that is just my opinion.