The only reason I’d want 2 “pages” is so I could close it to protect the screen(s)… but that’s exactly what covers are for.

Apart from the tiny minority of people who might prefer the form factor/“book feel”, are there any actual advantages to having 2 screens for general reading?

It’s probably just for the people who want it. I have thought about how much nicer two pages would be in the past for this reason and for displaying sheet music.
I did consider less common uses like that, which is why I specified “general reading”. I prefer paper for my sheet music, but I’d choose something with a faster refresh rate than e-ink if I had to use something with a screen anyway.