I'm sure the sex stuff is already made - they could probably add it in NOW if they wanted to - but I'm ALSO willing to bet that the dev just wants to make sure the actual gameplay is in working order and well received, no point in putting out a r18 jrpg if the jrpg aspect of it is lackluster. At that point you might as well be cheap and lazy, and just settle for using RPGMaker with very few assests and even less creativity