spears just fit for the spirit of the theme they were going. Most vikings hunted and fought wars with spears. Also it is a weapon that makes sense in a war setting as they are valid strategic weapons. Against dragons they are equally valid. There is a load more that can be said why spears should have been in,, but the question that should be asked is "why not have spears?"
I can get behind them being useful against large beasts like dragons or even bears. They might still swat the spear out of the way - people went spear-hunting for bears in large groups, unless they were insane - but it still might be reasonably effective.
My point is that a spear is not a particularly good weapon for one-on-one combat. As I said, historically the Greek hoplites main weapon was a spear for use in the tight phalanx formation, but if the phalanx were broken and a general melee ensued, they switched to their short sword for close-in work.
I'd rather have a bec-de-corbin or something like it, but I'll take what I can get. As for the realism, what will they do about blocking with a spear?
I can see the arguments that the more advanced, late-medieval polearms don't quite fit the time-period feel of Skyrim. As far as blocking goes, I guess it could be done, if you had a very short five foot spear - but it would be done poorly, like trying to block with a battleaxe or greatsword. If the spears in question were the more useful eight foot spears of the hoplite or even the http://en.wikipedia.org/wiki/Sarissa, well, not only should blocking be impossible, but the sarissa would be absolutely useless outside of formation combat, and even the eight-foot spear of the hoplites would be pretty close to useless outside of a formation.
Hence, swords.
Again, I'm not trying to shoot down the idea of spears being used at all, I'm just trying to give some realistic points about them. Hell, put them in; I'd love to have an eight-foot long spear enchanted with an enchantment against dragons or something. My Nord warrior could carry that into battle, along with a shield, axe and bow and have some options. But don't fight against the idea of limitations; afer all, it's the limitations that make the spear unique just as much as the strengths. Without unique limitations and strengths, the spear just becomes identical to the sword except for a differing combat animation.