Personally, I don't really see the point from a purely pragmatic perspective.
1) First and foremost, consider the tactical use of a spear. It is a mid-range weapon. Swords are for close range, arrows for the long range, but a spear can reach out and touch someone potentially up to ten feet away. An enormous advantage if there's an idiot with two and a half feet of steel standing 5-8 feet away from you. Consider, however, that in order to maintain penetrating power at that range, you would need two hands. Using a shield and shield would drastically decrease the effective range. One hand thrusting a spear whose tip makes contact six feet out likely means a glancing blow and enemy who's now slipped inside. Tactically, spears were most effective when employed in unit formation. Think of the spartans, the phalanx. One man with a spear might be somewhat intimidating but a sword and shield can deal with such a threat. A wall of spears... well. In this game, at best, you're rolling two strong. You're not exactly King Leonidas there, buddy.
A spear and shield, frankly, might be great for... A DRAGON SLAYER. Gives him a bit of range to stay away from the teeth and a shield to deal with the flames. A quick precise strike to a soft spot. And you win the day. However... When you're not fighting a dragon (this is a majority of the game, after all) a spear and shield is much more limited. Would you hold it at your waist or over your head, both are completely different tactics and would affect damage, range, and accuracy. Should there be a function to switch that position?
2) Consider the combat system. The melee system is divided into One-Handed and Two-Handed respectively. Where do spears fit in? Should they get their own skill tree or should they be slots in the One-Hand/Two-Hand trees?
3) Would it really make a difference? I'm not sure that it would... Both the third person and first person camera systems wouldn be a hinderance for gauging the range of your spear. Using it as a two handed weapons is the only thing that makes sense given that it would actually give you a noticeable boost in melee range. But given the lack of mobility, what the hell are you gonna do when someone closes in on you with an axe?
4) With spears, wouldn't you expect other polearms? How about javelins/throwing spears? What about throwing axes? Throwing knives? Ninja stars? How about shoes? Do you want to throw a shoe at a dragon? Okay, fine. I kinda want to do that. My point here is generally that melee combat holds its own in this game and without a serious overhaul that adds a myriad of weapons, and likely a whole new system of skills and perks.
Would spears be cool? Yes. Are they really going to add much to the game? I'm not so sure. For me the implementation is the biggest question.
How would you implement spears? Do you even want them? Does Skyrim need them? Or is this just another "hey wouldn't it be cool if..." request. (Not that there's anything wrong with those.)