People are generally upset with our banks because while they accept them as basically essential, they don't approve of much of what they do.
The banks can and do screw me, from time to time, yet yes - I leave my money with them. I might not have an "obligation" to do so, but it becomes very difficult to go around them. Most employers prefer to pay with direct deposit to a bank account, for example. If you opt out? They might cut you checks which you've got to go to check cashing places to cash, and incur fees for doing so right off the bat. Then you incur the risk of carrying that much cash around with you everywhere too.
Try to make a major purchase and the country flags you as a terrorist suspect the minute you make a large cash payment for it! Try to take cash on an airline flight and again, you're flagged and pulled out of the security line. If you ever do try to make monthly payments with a business on something, they typically run your credit and find that your credit score stinks too -- since there's no record of you having your name on a savings or checking account or any other real credit history.
I'm not suggesting all of us think bank robbers are "heroes". I know I don't. There's still a system in place that those people think they're "above everyone else", bypassing it, and costing everyone else in the long run. (Banks that lose money are covered by FDIC insurance, but eventually -- it's we the taxpaying public who gets to pay to keep that insurance program going.)