I don't get the drastic damage Grohk changes. The buffs you proposed won't really make him broken. Although I do think that he would need even more to be viable. I think the two healing talents should be put together in a balanced way so that you don't loose the ability to heal flanks. Plus, then we get tank Grohk back with Wraith.
Rampant Blooming is such an unnecessary talent tbh. If anything he should gain a third source of healing like Ying. For example, hits with the Crippling Throw could heal allies close to the enemy that got hit by it. But then again you run the risk of deathball meta when it's a good talent.
Wraith hasn't been in the game since Beta what are you talking about... The changes are highly necessary, so people will actually consider playing him as an actual healer again for the first time in actual years. The changes are geared towards that goal in mind. Plus, do you really think that Maelstrom should always be the only viable talent?
I'd rather run the risk of deathball comps once in a while popping up than run the risk of having a talent that actually has no reason to be picked whatsoever.