Well the short answer is, I just dig how they look on girls. The not so short answer is:
Basically they're worn by either punk/skater chicks, or that's who they are most associated with I think in terms of female wearers. Punk/skater chicks are hot, and they have this image of being a little bit on the bratty side (think Avril Lavigne). Naturally, bratty/mischievous girls are very much deserving of having those sneakers removed and getting the vulnerable, hypersensitive bottoms of their feet tickled, causing wave after wave of hysterical laughter which they are helpless to supress.
I like that answer better.