Healers need to actually matter in content that isn't the highest difficulty. Damage also needs to be more common and unavoidable.

I had a run of the lvl100 fieldstation dungeon the other day, where it did not matter that we didn't have a tank (he kept disconnecting) for the first boss, because the thing was too busy casting easily avoidable big attacks instead of hiting anyone. That's current content, highest level dungeon you can run, and we weren't even threatened as 2 dps 1 healer. That is beyond dumb to me.