I wouldn't say it would be a bad thing to make each biome after the previous be a little stronger in terms of the armor and DPS gains, and also increasing the mobs dmg and health to compensate. That way it's more of something you should feel necessary. It'd be a pretty easy way to solve the problem.

When you go to make a new armor from the new biome you enter and seeing that armor be equal to the fully upgraded armor you wear, at level 1, kind of tells you there's a bit of a problem.