I think it really depends on the social culture in which you practice pickpocketing.
Americans are renowned in England for their friendly nature and hospitality, therefore i think that they wouldn't object to a perceived accidental bump. In England however its a different story, people abhor being touched and immediately get suspicious if someone dares enter their personal space.
Friendly and hospitable...maybe(depending on where you are from) but personal space? I find it the exact opposite. I find folks from England are much closer talkers than most Americans. And even that is suspect since most of my experience is with Londoners. Urban people tend to have smaller "territorial bubbles" than rural people and since England has a higher percentage people in urban areas there you go.