"I also don't agree that all sexual contact between someone over 18 and somone under 18 is wrong. We are much much too quick to adopt this one size fits all attitude and add a bit of morality to stiffle any dissent."

The problem with generalizations is that they always come back to bite you in the butt. I, of course, see that there will be exceptions. A freshman in college and a senior in college can have a good relationship. However, if there is a significant age difference 3 years or more, and you are talking about a high schooler vs. an adult, then we are dealing with issues of power not morality. The lack of experience of the high schooler and the lack of equality in the relationship makes it difficult and the older person usually has the upper hand. A high school senior and a college freshman in his second semester are very often quite different in levels of maturity, even though they are only a year apart. Kids do a lot of growing up their first year of college, or their first year in the real work world if they don't go to college.
Anyway, I apologize for the generalization. But I still believe that there is a big gap in maturity between most high schoolers and an adult out of high school. I don't claim to be an authority, but I have had some experience in this area. That's where I am speaking from.