AoE Healing spells cause 1 charge of High Tide, max 2.
High Tide: Empowers your Single Target spells to Cleave an additional 30% of their heals to nearby allies.
I actually like this. Chain Heal giving TW was a way to facilitate our change between AoE and ST healing modes as we would not lose TW stacks during CH-heavy phases. Now that ST healing in general is heavily unappealing, I'd enjoy to see mechanics like the one you propose that give some synergy and make ST more attractive and viable for AoE situations.
Single Target Healing spells cause 1 charge of Low Tide, max 2.
Low Tide: Your AoE spells have your Mastery applied as if target is 30% lower on HP.
Now this one wouldn't fit right to me. I'm not fond of Mastery this expansion compared to Cata, but it still has a big impact at such low % health. Unless they tuned down Mastery scaling, our AoE would be pretty sick per cast. I'd instead prefer if we could get some more AA love, at least in Chain Heal.
Healing Stream Totem cd increased to 45sec, duration reduced to 10sec.(not just another whack-a-mole CD).
I have a love/hate relationship with HST right now. I prefer it over the older version, but it still is too passive despite requiring more management than the previous "drop every 5 minutes and forget". I might like it more if they made it empower our ST instead, akin to the Condensation totem thing, so its throughput was more dependant on our actions and was also more AoE-oriented than ST-oriented (e.g. HST lasts 20 seconds, 1 min CD. Whenver you cast HW/GHW/HS, HST replicates the 15% of the healing on other two targets).
I agree we have way way WAAAY too much passive healing. I'd love it if we could get much of our throughput separated from HR/HST so that we can be in control of it. It just doesn't feel right that you can get over half of your total throughput just from placing two spells down on cooldown.