Indeed, you raise another very strong reason to avoid using HoloCharacters for sexual gratification And also, the U.S.S. Enterprise-D is a government vessel. I simply cannot imagine a sponsoring government like the Federation authorising its holofacilities to encourage and engage - directly - in sexual encounters with its holocharacters. What I can see being sanctioned are romantic, or even fetishistic settings - both indoors and outdoors. Like certain Honeymoon Suites you'll find at expensive hotels, around the world, sometimes. Simulations of tropical islands like Hawaii, and so-forth. The understanding, of course, is that yes, Starfleet personal are going to have sex with eachother in these environs, most likely. But for the Federation to act as a sort of Institutional Pimp, that's extremely hard for me to accept and if I were a producer of the show, I would fight very hard against that.