I would be perfectly happy if all seasons did was change the lighting cycles, and mechanics in the game to actually drive time forwards. It's pointless if you always play through the game during two or three months. But yeah, I'd like seasons like that and holidays to go with it. For those that "makes a choice on when", choosing when to become a vampire could have meaning to the game. I really wouldn't want to be one during the summer
For comparison: Arma2/OA has seasons according to island location lat/lon, moon phases, but all it affects is the lighting. I think it also have tidal waves caused by the moon (I know it had in Arma1). FSX has seasons that affect textures, but I don't think that would look too nice in Skyrim.
Maybe some day. But I don't think Skyrim will be it.