I dunno flyin'meister.....I think they like their bods.
That's a given. But there is more to it than that, because plenty of women in their 20s & 30s have bodies just as nice as a teenager and can look just as young in the face. Having been a teen who was victimized by some older guys, I know they like the power/ego trip involved in such a lopsided relationship. If it was simply the killer bod they were going after, they'd probably not risk getting in trouble with a teenager and stick with women their own ages.
I just did some checking. Sandra Dee was only 16 when she and Bobby Darin wed. He was 8 years her senior. The divorced in1967.