Well, most people understand that dancing entails a certain amount of intimacy, but it is "fake" intimacy. The kind that has no strings and lasts only as long as the dance. There is safety in that kind of intimacy. I dare say that most girls would be very wary of a guy that tried to touch them (in the ways that dancing sometimes entails) with no preamble or introduction.
Dancing = expectation of intimacy
Chance meeting on sidewalk does NOT = expectation of intimacy.