I don't see a problem for healers here... Back to gorge times, healers only playing druid/Warden, priest/knight and priest/warlock. Nobody complained about mana and these classes had no mana retention at all and nobody statted wisdom -> less mana regeneration.
Healers need to use buffood soon (ok, just 1 healer in group with max wisdom, if he/she plays d/p or p/d. The other one can still leach), that healers don't full leech anymore
It's bad for ppl who didnt stat full wisdom for more HP/def. They "need" to restat everything, which is kinda bad, because the whole utility of wisdom is not only coupled to heal amount, but also for buffing the raid.
The idea is very great in my opinion, but it is like a mage change where wisdom is giving 2 matk. That would be a big shitstorm here