I agree. I hope they have some great creatures hidden in their pocket for later...maybe not as weird as Morrowind's, but still, something more original.
what is funny is that some of the most popular creatures for Morrowind added by mods were farm animals and real life fish species, I suppose there was enough weirdness in the vanilla game and that people missed "normal" animals

With Skyrim it could very well be the contrary, modders will have to come up with new concepts of creatures... because all the "expected" creatures (dragons, mammoths, trolls, giants and horses) will already be in.
Seriously though, Spore has shown that it is not that hard to make totally new creatures! Dungeon Siege also had original ennemies (regardless of what people thought of the game), and even the Pokemon franchise has spawned hundreds of new animals.... it can't be that hard for Bethesda to come up with 5-10 new ennemies, can it?