Qualified immunity is what prevents you from personally suing each member of the planning commission to pressure them in to reversing their decision. Think of it like the legal system throwing an exception, we aren't even going to consider this because your beef is with the city not an individual employee.
Police have qualified immunity because otherwise they would face personal lawsuits every time they wrote a rich guy a speeding ticket, or a convicted murderer has nothing better to do but get his law degree in prison.
In my opinion, qualified immunity is _not_ the problem. If an officer does something in their official capacity that is wrong, it is up to the department and the DA to deal with. Just like if the hypothetical planning commission did something illegal. Unfortunately police unions prevent that from being a viable option.
I think the best way forward is to force individual officers to carry liability insurance that covers settlements. This will have the effect of pricing out repeat offenders from the job.
Those other 3 officers (and the entire department) need to have skin in the game in that situation.
Yes retired officers should also be "reaping what they sow".
I don't know if would work in practice but there are multiple reasons to recommend it.
edit- just to be clear this would have to be negotiated as part of the union agreement and not something a court could just do.
The police pension funds work the same way. If the Minneapolis police pension fund was sued tomorrow and wiped out, the city still owes the police their pensions just the same as before. The money to pay those obligations has to come from somewhere. I suspect that it would come from the city.