I especially hate it when a character is called the actor as if that's funny.
It is funny, when the actor's mannerisms or pretty face are more prominent than the character's traits less associated with the actor. That's kind of, not how it's supposed to go
But I do agree otherwise about referring to characters with their actors' names. Suits that with Ten it works as an abbreviation of Tennant too so you can't really separate the actor
I think why it's not nice to refer to characters by their actor's name is that, it sounds like the actor is nothing but the character hers playing. And that's not nice. Even if I have no idea who else they might be.