Traffic signal systems designed to optimize driving make walking around the city 20% slower.

I would not assume that this is crucial to people's decisions about whether to walk or drive. It would have some effect, yes, but sometimes the effect would be that they take the bus.

If we change the design to favor pedestrians more, I would not want to take it to an absurd extreme. I as a pedestrian (which I usually am) would rather wait a couple of seconds than delay cars for ten seconds.