Level scaling doesn't necessarily mean "guaranteed challenges." It usually actually means "bland/samey gameplay." In contrast, with a well-balanced non-leveled system (not easy to do, but very much worth the extra effort), the game world feels more real (as the entire world doesn't match itself to your current level for some inexplicable reason), while a wide variety of challenge levels - including as well, at all times, challenges roughly equal to the player's level - are available throughout gameplay. This can also free the player to actually choose a path that may be a little more difficult earlier on, but win a tough (i.e. slightly "over-leveled") fight through strategy. In my opinion, that feeling of satisfaction and accomplishment is core to a good RPG.
But I've seen this argument devolve into endless back-and-forth on too many forums... suffice it to say I'm very, very glad Larian is taking the more work-intensive but much more rewarding non-level-scaling route with D:OS. Though the industry finally seems to be moving past the level scaling system, there are plenty of other games out there that still have it. But this ain't one of 'em.
