I delayed the main quest for quite a while, until I reached level 12 with my archer/stealth character. In a game that has leveling, there should be some stuff to aspire to at higher levels. While this makes sense for random dungeon and outdoor exploration, it makes less sense for, say, demons from hell or veteran city guards. A level 1-3 character has pretty much free rein to go where they want and a good shot at killing anything they want. It would seem that the "minimum level" concept was maybe not used as much as it should be.
Undoubtedly the rest of the game will provide further insight into this issue.) (Caveat: As I write this, I have only played the game a moderate amount with almost no progression on the main quest. While I still believe this, there are clearly some issues with how they implemented it in Oblivion. I have posted below on level scaling and my belief that it's a good thing. (The main forum has a front-page turnover rate of about 2 minutes, making it impossible to maintain any sort of discussion for any reasonable length of time. Normally I would look to post something this technical and game-specific on a forum, but I have been unable to find an Oblivion forum with anything approaching reasonable discourse.