There are other shouts that can only be accessed from other factions like the Thieves Guild too. It's not just the College of Winterhold.
It gives replay value to the game.
While true, it can be a minor kick in the teeth. I'm not a big fan of going through opening sequences, but thankfully Skyrim's is pretty minor compared to other games (Dragon Age for instance).
Was one thing I always liked about Oblivion. Didn't matter what decisions you made (Shivering Isles aside), you never limited yourself. You could create one character, ever, and do everything.
*EDIT*
Just realized I may sound exceedingly stupid, I'd like to point out I only bought the game the other night. Looking through achievements, it seems like the game forces you to choose sides. If this is true, and based on decisions your limiting yourself to certain shouts, or anything, my response is on that.