I completely agree that SPD is petrified. I've live/worked in downtown Seattle for a while - and while I think some of the 'scaryness' is overblown, it's hard not to see a change in the trend over the past few years.
SPD has an incredibly strong union, which is where the real problem lies IMHO. A bad cop almost literally has to murder somebody before they can fire him. DOJ took note of the resulting abuses, but of course they aren't interested in going toe-to-toe with the union, and neither is the mayor.
It's a complex problem but it stems from a fairly ordinary failure of leadership, and that particular buck stops in the mayor's office.