Healers being "redundant or "useless" depends on the party. I won't claim whether its,good or bad design but as someone else stated there will always be someone messing up somewhere. If you feel you want to play the game without healers I say go for it. Most other players will opt to keep em in their groups as per design.

You give healers more dps option they just become green dps (in which id imagine the next point will be "why not just play a dps"). They nerf tank survivability you end up with upset tank mains.
Idk, I don't see a clear cut path