In Diablo 2 there is a similar system, where various skills/game mechanics and items work differently in PvP. IE Resistances, Equipment, Skills, etc.
Heck some skills were completely disabled in PvP on Diablo 2 ;p
It is a very helpful system.
That may be so mewi, but that system was designed to be that way by devs that give pvp due and proper consideration. Cryptic didn't design the system that way, it would kill them to do a redesign to make it that way, and they would have to care beyond more than Borticus checking in from time to time (as in a sr. management change needs to happen).