The 20% Healing nerf may justified for some of the healing skills in CP pvp. But arguably not for all of them.
When it comes to non-cp PVP the healing nerf was completly unjustified for every single healing skill in the game, since it was already way way below of the CP equivalent. You get higher stats due to CP passive and CP revovery/cost reduce/tankiness allowed you to run higher damage resulting in higher healing as well. On top of that you can put alot of cp into healing taken/healing done/crit healing done.
None of which you can do in no-CP PVP. The difference obviously varies between every build. But for example when i ran a healing tankblade my malvolent offering crit healed for up to 17k in CP and 8k in non cp. More then doubble the value, without really changing the build or the target. Yellow Vigor only heals for 600 every 2 secs on a 4,5k wd DK, no one would ever pick that morph.
Seriously Zenimax you turned non-Cp into a meta chaser or instant respawner choice.