I live in a global city (New York) and there are many crowded and bike-unfriendly spaces here (subways, buses, movie theaters, bars, restaurants) where one could not even bring a 16" folder inside. There is also a high amount of bike thievery, so keeping one's "personal mobility device" on hand and in sight at all times is really the only fool-proof solution to theft (at least until NYC rolls out a comprehensive bike-share program).
I think living car-free is not only a more sustainable solution to pollution and climate change but better for our own health (exercise), everyone's safety (think of the number of car fatalities per year), and the design and enjoyment of our communities and cities, which have been ruined by decades of auto-oriented planning.