Expansions come with new mob types. Those mob types are usually rehashed until the next expansion, aside from unique looking bosses. So, guess whether the same applies there.
You won't buy into my "guess-work", because trololol.
But I must say, a generic "more could have been done" is an excellent criticism. You don't even have to specify, you can just go ahead and bitch, regardless of what is said and done.