Oh right, because the futa / femprotag / transformation games are so rare and original.
Compared to incest with sister, yes, without a doubt.

You're also mixing completely different things. Futas are
stup.. (nah, let's be nice, I probably just don't understand it correctly). Regular female protagonist is just that, normal separate thing. And transformation tag seems to have very very broad meaning, so it doesn't mean much.
So I'd still say that author's (<- don't forget this important part) vision is pretty original. I mean otherwise normal world with normal people and just this one weird aspect. I'm interested to see what he does with it. And also a bit worried that it will fail, but it's not wrong to try.