Well Ten and Rose definitely comment on the fact that Gwen looks like Gwyneth, so this is another one of those things where it was ok for RTD to do it but not Moffat
You're assuming people didn't roll their eyes at that moment?
Actors play different parts. Sometimes in a long running show, different parts in that show. It doesn't need explaining to anyone except those whose grasp on reality is pretty shaky. (And they won't believe it!)