You've been watching too many caper movies. 95% of robberies are covert robberies where people leave a note and want to get in and get out without causing a scene. No Guy Fawkes masks or drawn guns, just a note demanding cash and enough of a disguise to conceal their identity without people saying "hey, who's the nutjob with the ski mask and the Glock?"

I can't find any rigorous studies on whether policies like this help reduce robbery rates, but this article mentions that robberies went down in Missouri after instituting the policy, which is not to say post hoc ergo propter hoc, but to shift the burden of proof to those who insist policies like this must be worthless simply because they're inconvenient or somehow infringe upon liberty in some meaningful way. There's at least circumstantial evidence that the policies can be helpful, and I find these slippery slope from taking off your hat the bank to tyranny arguments unconvincing.