I think 9ams are fine, if you live with people who obey the 11/12 curfew, don't get fire alarms throughout the night, and live relatively close to your classes.
But if you're kept up til 3am or later by other people's parties, woken throughout the night through their drunken antics, and then have more than a 30 minute journey to your first lecture, I can see why they might not be so attractive.
Personally, I love 9ams this year, even though I have to leave by 7.30 to get to them on time, but then I'm working 6-10am on days where I'm not on campus, so leaving at 7.30 is still a lie-in.