It is actually literally degenerate.

"Given to vice" is one of the definitions of thzt word and I would argue that sex exclusively for pleasure (without the option otherwise) can be classified as a vice as it is a corrupt state of the act of sex. Sex, fundamentally, is for reproduction whether pleasure is involved or not. You can argue that pleasure is a part of the whole act, and I would agree, but when taken to the extreme where there is no option for anything but pleasure, my above argument stands.