Just an idea; I'll admit I haven't thought it through a huge amount.
It seems to make sense though; if done right it could stop some things from becoming broken again after this balancing, as HP and other stats march ever higher.
I'm thinking potentially for all kinds of things:
HoT ticks
DoTs ticks (in PvP)
Heals
Nukes (in PvP)
HD
ND
Layers
Specials/normal hits even? (in PvP)
OK for some things it's not appropraite, but for others I think it opens up some interesting possibilities.