Ultimately, while it is slightly obnoxious, it doesn't bother me that much because under no circumstances would I ever play the trans route anyway.
Obviously if you're saying this.
It's obviously just being forced in as a fetish thing, which is of course what the trans route has been since the beginning.
Until season 2 the trans route was objectively better written than the cis route. So much of Shauna makes no sense of the cis route, and playing through the trans route after all of a sudden everything makes sense with her. If anything the cis route was tacked on to double dip with people not into trans content, although the season 2 writing has improved cis Shauna quite a bit.
Now for what it's worth I disagree with your point regarding Jamie Shauna specifically. The Jamie Shauna lesbian route has really just been them exploring their friendship in a new way that also excites the MC. The latest update makes it pretty clear that Shauna is into it too, I won't spoil it but the lesbian scene is very reminiscent of the gazebo scene except with Jamie making her cum instead of the MC.
Also there's quite a bit of difference between someone fucking your girl, and one of your girlfriends fucking your other girlfriend with you. Dislike the trans content all you want, but that's not what those scenes are about.
Otherwise I do kind of agree in general. I pretty well always go for the lesbian path in harem games but the Bailey Rain bit, Bailey made it way too clear way too many times that she wasn't into Rain like that that the start of the path just felt like soulless fetish fulfillment to me. Like the only reason she'd go for it is to please her boyfriend. Maybe the next bit with them will be better in which case I'll change the variable for that but otherwise I feel like BD wrote himself into a corner trying not to piss of lesbian haters for the lesbian route with those two to feel genuine.