I think people are overstating her danger by quite a bit. She did not hit Faye. She did not miss by accident. She was sending a clear warning to someone who doesn't take verbal or non verbal clues or requests to leave her alone. Bubbles is well aware of that fact because that is exactly why she got herself into the situation at the party in the first place. Faye kept pushing and pushing until she found the right button to mash. So the only thing Bubbles had left as she saw it was a direct physical threat. Then she went home and tried to work out her frustration on some heavy bags. It didn't work, but at no time during any of this did she lose control, or was actually a danger, aside from freak accidents with flying masonry. Given the fact she can put her fist through all that leather and sand, it's quite likely that she pulled her punch on the wall, using only enough to demonstrate her strength.
Also keep in mind that Pintsize didn't have a military grade chassis taken from him. He had an active military weapon. When you are discharged, you keep your kit, but you don't get to walk off with the rifle you carried, or the tank you drove. Momo has stated before that legally speaking, the chassis an AI inhabits is their own. I'm sure there are limits to that, you wouldn't let the AI in charge of a nuclear submarine keep it when they decide to change jobs. Those things run in the millions of dollars. Who knows how much Bubbles' chassis cost. It's entirely likely that she bought it out with her accumulated pay when she left the service or was discharged.
As far as people just letting her walk around, she did say that 'better minds have than you have tried' to 'fix' her. The implication is that she has seen a robo psychiatrist sometime in the past at least. While I imagine Bubbles was less than open and cooperative dealing with them, they didn't judge her to be a danger to herself or others at least.