Iris's sex scenes got quite repetitive lately,
I suppose, but let's be honest, the same thing could be said about sex scenes with every other LI, because there isn't exactly that many ways to suck a dick or take it up the ass, either. But they all still got fully detailed and rendered scenes of said activities, some of them more than one. So having just this one pairing out of all of them neglected in such manner feels jarring and disappointing.
Regarding fleshing out the NTR path, do you mean Iris showing up at Black Whip? I couldn't really find anything else in the script (Iris telling Blake she had fantasy of Stewart fucking him, while technically on NTR path, comes across more like some sort of a weird reverse-NTR than anything)
oh, on this note, there's a small bug in that Stewart fucking Blake scene: the script calls
scene 019firstsceneiris13
twice, while the second instance should be
scene 019firstsceneiris14
instead.