I can't think of a single game that manages to have enemies correspond to your level rather than area or story progression actually contribute to the game. It just makes trying to get better gear ultimately a pointless task because the enemies get strong at the same rate so you might as well stay weak.
oh yeah.. they could've made that dropoff less harsh i think, let us struggle to beat an enemy that's over-leveled and then schlep around some gear we can't use for 10 levels if we want, dammit. I guess they didn't because that breaks their gameplay loop but you'd still re-engage with it along the way and it would make some challenge runs more feasible.