It would be  nice for people like me who liked the original Rack game because we didn't have to be (nice) to subjects to get them off. It would be nice to be able to customize our subjects appearance, likes, and be able to adjust their attitude and change the rate user and subject orgasms. It is a major turn off with all the new elements to appease the subject, just for a disappointing orgasm, and it will penalize you for not using their preferred sexual preference. I understand there are subjects you can do whatever with, but I like how the he original Rack played. I kinda like to be a dick to the subjects too.

Things like eyepatches, customizable collars, earrings and piercings, bracelets, necklaces etc.

an option for a genital "slit" that the penis will slide out of when erect, as often seen on reptile/dragon, bird, and sea-creature characters

Can be penetrated like a vagina

it'd probably be hard to implement, but i think it'd a cool touch to add some "physics" options, where if the penis is particularly small, it can still be penetrated while erect, or if the penis is too big it won't fully retract back into the slit while flaccid

There should be a category for humiliating the subject while forcing them to cum. as its own specimen I mean, since there is going to be mind control you hypnotize them afterward to prevent any ill effects of having been essentialy broken during the session (wether they remember what happens or not)  

Lots of Bras, Panties, and Swimsuits to be worn

I would like to have the ability of letting a tentacle makes its way through the gastrointestinal track, starting from either end, and that would be pretty cool if this game has that feature.

Inserting a characters muzzle into another's pussy/ass

i think you should add in-game cheats like in rack 1 and allow mod support