High level traits are intended to adjust actions to make use of them in higher level content, but not lower level content.

Across the board fixes are generally about playability, not necessarily power. For example, Aspect Mastery is largely a playability buff, though you'll probably see a general numbers improvement at lower skill levels just because of the way it works.

This is the same thinking as the Tank "Melee Mastery" traits, which are there to increase a tank's relative potency moving forward from that point, without increasing their power before that point.