Comment: It's math.  Cars go slower  -  they have fewer accidents of any kind.    Humans make bad decisions, both drivers and pedestrians.   5 miles an hour slower, in a mixed use area, is just common sense if your goal is to reduced deadly accidents.    Why is this even an issue of contention?

I'm not excusing stupid bike or pedestrian behavior.   I've seen plenty of it in Eugene.  Nothing like an unmarked, no lights bike at 10 pm  to scare the crap out a driver.  Nothing like an idiot in a Toyota cutting you off changing lanes either.   How about the little 'duel' of racing cars through traffic.  Road rage anyone?

But I don't know of many bikes, or pedestrians, killing the driver of a car at impact.    Like it or not, the mass of a car is a significant cause of death.   

To expect perfect behavior in human beings is a false hope.     Drivers, bikers, pedestrians may all have an extra second to correct their mistake with a lower speed limit.