DC has a good point. All drugs (and yes - these are drugs - a controlled substance) have side effects - hell most holistic herbs and such have side effects. They can interact with whatever else you maybe taking and not everyone tells their pharmacist or doctor what they're taking. What harm can aspirin do - or how about my daily vitamin? A lot.
As far as the Morning After Pill goes - I still believe this should be by prescription only. I know that may not be a popular belief but it still has hormones and if you aren't observed while taking it you can get in a shit load of trouble.
I know of a woman who used this treatment and abortion as her only means of birth control... now she can't have kids and her cycle is completely messed up. That's a bit extreme, but if the Morning After Pill is OTC girls will use it as such. It's a human trait to try and hide what you're ashamed of, and that can be very dangerous. What happens if the reaction you have is a hemorrhage? If you aren't under care at the time you could die. Is death really a risk a person should take to save face?