I see both sides.
I've talked about this with my dad on several occasions. He used to give me the "Back in my day..." talk when I'd have three days in a row off from one of my jobs. "Can't pay for your books if you're not working." Well, duh. But you can't work if your manager isn't scheduling anyone the hours they need. I actually started going in and cleaning the stock room or organizing the cooler off the clock just so I didn't have to listen to him wax about how he had all these hours at my age, so what's my problem.
But I stumbled onto another lesson in the midst of it: when you make yourself indispensable, the hours come. Then the responsibilities. And if you keep it up, they're offering you your very own store at the age of 20.
And while I can only speak anecdotally, the lack of hours is what's driven several of my students to find new jobs. What good is $12 an hour if you're only getting 15-20 hours a week even as a reliable employee?
It's very good for people that only need 15-20 hours per week. All kinds of situations.