I don't mind for other people touching my bags, if it is a gentle touch. However, I am irritated by other people hitting, bumping to, or scratching my bag.
ITA, most time my friends who want to see/touch/try on my bags are very gentle with them so i really don't mind. I get very annoyed with people i hardly know who handle my bags very roughly though (case in point, a friend of a friend, who i don't know well at all, started RAMMING her fingers into the quilting on one of my classic flaps because she wanted to see if the quilts "popped back up" after being pressed... i was REALLY peeved!), because it just shows a gross disrespect for other people's belongings.