Admittedly, screwing these dolls has been more entertaining than I expected, as you guys still have an edge over competition (as far as I know) with the physics simulation in this game. However, no one enjoys nailing that one chick who just "lays" there, like a lifeless corpse during sex. At least I dont <_<

Chicks use their arms/hands to express themselves when they're not doing the work.
Come in too fast/deep and they'll put their hands against you so they know when to expect you next time.
If things are cruising along at a favorable pace for them, they'll relax and put their hands above their heads in missionary.
The ones who are more interested in pleasing you will fondle their tits, or hold their legs back for you, so that you can see things better.

And the reaction to receive a cumshot is like... essential, I think, as no one just takes it without any reaction, even if its subtle.
Things like this are necessary to achieve realism, and if you guys don't do it, someone else will swoop in and do it instead.

Hear, hear!

I concur

Going off of this, they don't care if you don't listen. If they don't want you to cum inside and you do, they just take it. If they don't want a DP and you do, they just take it.

At the very least there should be some negative feedback dialogue if you don't do as you're told, if not (as you said) actual physical intervening.