Well, I was basically agreeing with the idea that bikes and cars should ideally be separated. I don't know if the laws are even formally different on these streets, but it kind of communicates to everyone what they should expect and helps cars and bikes stay out of each others' way, which they both want.

I also think that residential streets are often under-utilized, though (mostly existing to connect houses to thoroughfares), and I'm skeptical that drivability is being sacrificed all that much—I still don't have statistics but IMO there are plenty of places to drive and I don't find my neighborhood hard to navigate by car. Just one person's experience, but I think it's a nice, cost-effective solution that I hadn't seen before I moved here.

(I have a bike and commute with it most days, but I also have kids, so weekends are all driving, and I sometimes need to drive to work too, for one reason or another).