Healers are more vital to the groups survival than a dps. You just don't notice immediately if somebody does poor dps, but you will notice immediately a newbie healer. That is all there is to say. Because of the matchmaking you get either a bad dps when you queue as healer or a bad healer when you queue as dps/tank. The chance for it to happen is the same and after 1000 runs it is. The only difference is that you will most likely die with a newbie healer, with a newbie dps there is still a slim chance that you can win, but this depends largely on the enemy grp.

Classes can already oneshot Healers with the right combos, why suggest heal decrease and dmg inc increase?, people would die every 10 second.
With enough dmg done you will get interupted and that multiple times in a row is pretty deadly, also they can silence you, they can stun you and they can knockback you, you can sleep them or root behind a wall with holmgang or cc... And all the resists are like gone after 1 minute, so I am not so sure about the "missing cast interruptions".

I play monk often in pvp, most people try to just burst targets down, this works okay usually but later with good healers you really need the perfect burst for it to happen... so I rather switch to interrupting their burst phases as much asap in the downtimes. Stealing buffs and good cc during enemy buffs is the real key, feel like this has a much bigger impact on the match as everything else.

I would want new feast maps (cant be that hard to map........) or other scenario like capture the flag(but not 4vs4 now) with lots of random upgrades and usuable turrets around the map