When it comes to Skyrim, I will be sorely annoyed if you get around the terrain like in Oblivion. Jumping/Running up a 70% angle hill, running downhill, swimming in water as fast as you run etc. and other assorted nonsense.
Skis are a great tool and immersive. The picture is a famous painting of Birkebeinar. They were rebels to the throne of Norway at the end of the Viking era, during the civil war of Norway (which would eerily coincide with the lore and timeline of Skyrim).
My point is, that not having skis in Skyrim would make little sense, being an ancient tool used in the real-life "mirror" of Nord culture. A referencing faction to these guys would also be amazing, although I suspect something like that is already in - skis or not.