All that needs to happen is revert gear back to WoD system. PvP gear increased by 30ilvls in PvP, while PvE was reduced by 30-40ilvls I believe. That would stop pretty much all these PvE heroes from mongoing people down with the M10 gear and CoS gear. Also just disable all PvE gear equip abilities in instanced PvP and everything will be back to normal.
I get the fun of them in PvE and stuff and why blizzard implemented them so people could have some variety but just disable them in PvP it’s not that hard. The code is in the game from Legion.