SAO basically did this amazing thing in Season 1 where all the premise sounded like it should be some shonen-battle-harem-girl bullshit, and DIDN'T DO IT.

Having it show up suddenly in Season 2 is sketchy as fuck. The incest crush might have worked if it wasn't a "thing" in anime overall, and if they didn't go out of their way to have to highlight "oh, but you're adopted so it's really ok wink wink".

It's like seeing the author's personal issues getting poured onto the table and it's not cute at all.