Is qualified immunity really the issue? The general impression I have is that PDs/DAs straight up refuse to investigate/prosecute abuses of power. It's not like we have a bunch of cases where the case was airtight, but the officer was being acquitted because of qualified immunity.

Qualified immunity affects civil suits, not criminal prosecution. If the police department or district attorneys refuse to investigate or prosecute, qualified immunity means that cannot sue for recourse (under some qualifications).

Might as well start somewhere.

Civil torts are a check on the criminal prosecution system when it becomes too lenient.