Wider streets are good for getting a lot of stuff through - up to a limit. Los Angeles and Atlanta are full of massive highways of cars that barely move.
Larger streets also hurt street side commerce. Nothing chokes off wakability and storefront business vitality like multi-lane one-way streets.
EDIT: I feel compelled to mention from my experience that in Rome, the most active streets with the most vibrant businesses were not the arterial roadways - those seemed to mainly serve large businesses, government buildings, and tourist traps - but rather the tiny twisted streets in place for many centuries.
I think open straight streets don't fire up our spacial memory in the same way, and as a result aren't really "places" in our minds in the same way as more intricate and varied environments.
Larger streets also hurt street side commerce. Nothing chokes off wakability and storefront business vitality like multi-lane one-way streets.
EDIT: I feel compelled to mention from my experience that in Rome, the most active streets with the most vibrant businesses were not the arterial roadways - those seemed to mainly serve large businesses, government buildings, and tourist traps - but rather the tiny twisted streets in place for many centuries.