I think of of the reasons teens are a bit too boring for me is I don't like to micromanage my game. I love to sit back and watch what they do autonomously. I don't have pre-made stories that I have my sims act out. I love watching what the AI makes them do. I actually hate it when I have to cancel some action to make them do something they should have done themselves, like eating or going to the bathroom when they are playing an instrument or on the computer.
Maybe I just play totally different than most people? I don't know. I just figure if Maxis worked so hard to make a "life like" AI what's the point of not using it? Also, if I wanted to pretend my sims were feeling or acting one way when they clearly aren't, I'd just write a sims story or go play with some dolls.