I disagree with this suggestion entirely. Why?
Because players should have a free will of what they want to do. If they want to rob the bank to get cash then they should be able to do it, if they want to go do missions, find collectibles, fish, do achievements or have a job and play as a cop or any of the other jobs then they should have their free will to do this as well. Limiting players to rob a bank is just like you should limit them from doing other activities. Also, what's the use of limiting people of robbing banks anyways? They will all end up in crews, they might not be in the same crew, but little from each crew will be just as much criminals as it is now, probably even more deadly.
Meanwhile it is true that there is large people that want to rob the bank at some times, but if other canon mechanics are added such as drug dealing or casino heists. It will be less crowded at bank.