The landscape in morrowind made it feel bigger than it was
The landscape in oblivion made it feel smaller than it was
They've already said several times that the skyrim landscape makes it feel bigger

personally I like the world size in the Arma games or the original operation flashpoint, it would make horses more useful if the distances were larger too...
the only thing to watch out for would be quest design...dont send the player all over the map on sidequests..

not gonna happen though..the world is built and its oblivion sized

Were I a younger man without a career, yeah make it bigger. But no...I'm happy with the size to filling ratio. I like to think it's a double stuffed oreo now. Perfect.