Tradeoffs. Can't have open world, mobs that do NOT scale with level, without players able to wander in to higher level areas. The traps may or may not kill an appropriate level character (depends on fire resist, constitution x lvl).
I personally went this route early b/c I wanted to see if getting a plot item might give different options. It didn't. But the idea of doing higher lvl areas by choice in an rpg is part of the appeal.
