I almost want to make the damage graph 15*level, which briefly cuts above Elite at low levels and gets overtaken by Easy around level 80 or so.  This isn't that great, because Veteran is mostly balanced, but gets harder around 30-50 in the current state.  The described change would make the tundra stage a lot harder, and possibly nerf enemies a bit too much going into the last two acts.

Balance is kind of a pain.  ... The amount of testing needed would be large.

Indeed, balance can be a long long process.  Such a fundamental change would require a LOT of testing however you go about it.  I imagine Runic had many balance iterations just to arrive at the current numbers.

So I would suggest before tweaking any numbers to play an unmodded normal/veteran game to 100 (preferably something other than a forcefield engineer) to get a feel for current high-level balance, so you can have a better idea of what changes may be necessary.  Farming shouldn't really be required if you play normal.