> It's no fun exploring
>an area designed for level 20 when you're level 40! Nor is it
>fun to level past all the cool challenges and experiences of a
>lower level character.

Go ahead and take the route and approach that you slowly level your character by exploring these areas and quest, thus gaining the xp. The main reason for not exploring at low levels is probably the fear of dying and getting into the xp hole. But not everyone has to play with the grind same mobs over and over way. In fact, I think that you can probably develop a better RP if you take the approach of adventuring where your RP takes you and let the levelling be a sideproduct. Maybe you could attain a lot better immersion that way.

Basically, if you aren't levelsitting for powerplay reasons, such as sitting at the rank where your character has optimized PK power on purpose, it's totally okay. The game starts at level 1 and there's no reason why you should rush to Hero where leveling stops. It can be a lifelong process if you want to be, with reaching a level actually meaning something.