As others have said in most games with sex pretty much everyone is fuckable so we've come to expect it.
Essentially, we're a bunch of Pavlov's dogs drooling when we hear the bell because that's what we've been conditioned to do.
Although I'm sure in a few cases some people expected sex options just because it would make sense by their logic.
Like, I was expecting an optional sex scene with the book store guy because I thought it would be in-character for Maiko to offer herself in exchange for protecting Savori.
I suppose for others there could also be a sense of "incompleteness" or missed potential.
