Cata Tree of Life Design Goal

What exactly is our new Tree of Life form supposed to accomplish? I know what's been released on it so far. I'm not asking about specific mechanics. I'm asking about *intent*. Is it a burst healing cooldown? A longevity cooldown? A PvP turtling cooldown? A damage cooldown? There's a lot of disparate effects in the current Tree of Life ability, and it's hard to tell which of them are supposed to be the ones that matter.

Every other healing cooldown has a specific vision, a specific purpose. Pain Suppression and Hand of Sacrifice save your tanks from big hits. Mana Tide Totem and Hymn of Hope keep you in the action longer. Divine Hymn and Tranquility help you play catch-up. When I read the tooltip for Tree of Life, though, I don't see any such vision inside.

Tree of Life seems like it's trying to be all things to all people, leaving it without a central purpose. And because it's trying to do too much, all of those things end up being mediocre. What is it supposed to do for us? Why is it trying to do half a dozen little things instead of one big thing? Why and when are we going to want to cast this tepid thing?