Goblins are native to Cyrodiil, so them showing up in Skyrim wouldn't really make sense. Plus, the Falmer (or Light Elves) are pretty much the same as the goblins, just a little larger and tougher. Plus they have a pretty cool back-story, if you take the time to read about it. I do agree though, that Skyrim should have a larger bestiary, but I'm happy. They have dragons.

First of all, there was Goblin in Arena, Daggerfall and Tribunal.
Second, Falmer are Snowelves.
Third, I'd like Goblins for varietys sake. The Skyrim beastery are really lackluster.
Seriously, no Minotaurs, no Ogres, no Rieklings, no Cliffracers (:sadvaultboy:) no Netches (near the Morrowind border) no Goblins and no variety in summonable Daedra. (Clannfear, Scamp,
Daedroth, Ogrim, Winged Twilights etc.)
But the game is fun, and I like the beastery that made it into the game.