Calimente says that one-way streets were a by-product of the expansion of freeways, and that today we know that faster isn't necessarily better when it comes to cities:
"There is much evidence that two way streets are good for business. It makes sense that two way streets encourage slower speeds that also result in drivers paying more attention to businesses they drive by. Cities large and small in the U.S. have been moving away from one way streets, primarily to increase economic development."
Calimente maps out Vancouver's remaining one-way streets (not that many, actually) and recommends that the city convert them back.