That said, when Louis Kahn proposed that cars be excluded from downtown Philadelphia, he wasn't exactly taken seriously. It is one thing to identify a problem, another matter entirely for people to change their habits in response.
We're addicted to oil, globally and locally. At least that's what dependence looks like to me, what it feels like on a good day. Even if we are convinced intellectually, it's still 'radical' to get on a bandwagon about walkable cities, pedestrian economies of scale, cycling/bike lanes, public transit. Even car-sharing is thought by some people to be a problematic paradigm shift: "My car, my independence;" "My car, my freedom;" "My car, my feelings;" "My car, my identity;" - and other ego-displaced confusions like those - are powerful intoxicants. Motorcycles are more efficient, more excitingly closer to the elements (air, especially) but the illusions they sustain are, I daresay, pretty similar.