I love the IT bags and would wear one. It is more the style of the bag that makes it young or old. I wouldn't wear a tiny shoulder bag, too young. Satchels and totes, I am there.
if teenagers have them.. they only got it because they are spoiled and whined for it! you earned the money, you paid for the bag, it should be yours..!
btw.. i would stay away from maybe the tassle line looks a bit kiddy to me.