That idea to swap Ascendance and Mastery, is terrible. You would basically never use Ascendance, unless you just wanted to top healing charts with Healing Tide, and Shaman's would simply stack the living hell out of Mastery.
i beleive blizzard should just rework/add to our tidal waves buff. Something like increasing our stacks to 7(encourages keeping riptides up) and allowing our CH to apply
a mini-hot to all targets hit besides the original target.
Or even apply a fulmination(probably more like BM hunter focus fire) type of idea to our riptide. Consume 5 stacks of riptide to make your next greater healing wave apply a smart heal(hot) to X amount of players in your raid group. I think something like the latter would greatly help our spread healing.