When I used to commute via company bus in the bay area, it mattered to me; also when I'm using my laptop out and about in the city, I'd prefer not to have to worry about finding a seat with a charger.

Of course, nowadays power banks are getting so cheap and lightweight, I just toss a couple in my bag, and don't really worry about it. I just ordered one of the Haribo power banks all the backpackers are raving about.