It’s been around for a looooong time. Edgar Rice Burroughs first book in the John Carter series, A Princess of Mars, has the hero running around Mars with a voluptuous naked woman. Every cover for that book has her in a teeny bikini just to avoid being censored, but Burroughs clearly was living out a teen inspired fantasy in that book. And I’m sure the covers of those books caused a lot of young teen boys to become interested in reading.
They got me interested in the art of Frank Frazetta at least. Prurient cover art has a long tradition in genre. What’s really changed is that the audience is no longer 90% male, so we’re no longer the target audience for all the covers.