This is a thing I have been deep into for many reasons.

1) You won't see the maximum level enemies or creatures until you get to a level when the game allows them, based on your Player Character level

2) You don't have access to all of the spells and weapons you might have if you were at lower levels

3) Your ability to use what you have is less, if you are at lower levels

4) Doing this easily doubles the length of the game, and therefore also the entertainment and overall value per cash spent on it.

5) The screwy ways that levels can be built with also the added caveat that you have to avoid quests means that you have to go to means you otherwise wouldn't think of

6) The method can be WITH or WITHOUT mods, but I prefer vanilla - if you were looking for a challenge, there it is.

7) When you top out - that's all you get. You can either work with it or not.

8) It makes you think a lot more than you ordinarily would.

9) I play on an XBOX 360 - there ARE no mods or console commands for it (if you use one too - that's a clincher)

10) The treasure levels increase...