This sort of thing does happen.

It's rare but not that rare.

The thing that makes it seem so rubbish in ROTJ is the tone of the film which is all over the place (setting the scene for the PT later).

Comedy Ewoks, comedy droid torture, burp jokes, puppet/CGI song and dance numbers etc, etc mixed in with accidental near incest, father Vs son limb slicing action revisited, giant Vagina dentata and the implication that Jabba does slave girls (check out the tongue action).

Sort out the tone of ROTJ and the Luke/Leia thing makes sense (there are clues to this being possible retroactively evident in ESB).

It's certainly less weird than a romantic scene between a really little boy and early teen girl.

George hasn't made his mind up if these films are meant to be for little kids or really warped teenagers and adults.

So he mixes it so it's not really hitting the mark for either.