One might consider the alleged Lewinsky sexual contract a bit vulgar. Consent carries with it the presupposition that an individual is capable of making up his or her own mind and of being responsible for his or her behavior. Historically, political struggles raged around who was capable of consent and who was in a situation of permanent nonage. Criminals were shoved into the nonconsenting category as well, as long as their criminal status was socially enjoined. But the folks in these various categories fought their way out of political and legal infantilization.
Children continue as nonconsenters, of course, although there are dissenters even here.
But this quip didn't impress the assorted radicals. As a society, we have made this determination, and that is why the age of consent for sex is most often, for most purposes, 16. There is something that strikes us as inappropriate, sordid, unethical, and likely exploitative about such a relationship, and for good reason. That a particular action or relationship is or was narrowly legal or consensual does not mean we find it good or decent or fair or reasonable. Take this one step further.