Wide streets are harder to cross and wide lanes means killer objects go faster. Putting one or both on a diet makes streets better for pedestrians. That’s my understanding anyway, and vaguely backed by casual observation/lack of experience counter-examples.
Related, I also really recommend http://acawiki.org/Street_Rivals:_Jaywalking_and_the_Invention_of_the_Motor_Age_Street (summary of a paper and a podcast retelling). Killers won 90-100 years ago, though they didn’t have to. We should use the beginnings of autonomous vehicles to legalize pedestrians in the streets and to ban human drivers.