I don't have direct contact with the developer and he is not even on this site to interact with us. However, I can make an educated guess that he is probable still learning the ropes with regards to the animations, hence starting with mundane stuff before applying what he learnt during the process to the steamy scenes. Need to get the perfect balance of fps, lighting, angle or whatever. I have no experience myself but I do know that there is more to animating a scene than meets the eye. It is more damaging to produce lackluster steamy scene animations than without one IMO.
Unfortunately, this is purely speculations on my part because I had only played a single release of this game and I don't have other release to compare with.
Duly noted, that the most obvious observation and direct will be that it is indeed less desirable and counter-effective to produce these teaser-type mundane animations over steamy scenes for an adult-oriented game.