The problem with your idea is that the class would only be useful if you were playing with others. True, lots of the time you are, but there are plenty of people that solo things like the story misions, and having a class whose super and melee only help others would be useless. At the very least, the super you describe should buff the users health regen as well of those around him.
Destiny does have MMO elements, but it is not an MMO in the traditional sese. Tryig to shoehorn in things from other MMOs just because 'that's how MMOs should be' does not seem like a good idea.
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Warlock has a heal class. There void class heals you. Killing an enemy with energy drain heals you and damaging an enemy with your grenade or nova bomb triggers energy drain effect which heals you