Healing is less valuable than pure damage, speaking from experience. Most healing in the game is overvalued by R&D and its balancing methods, and therefore healing does not often restore enough HP to prevent a KO by the defending Pokemon when your attack only does 90. And 4 energy to attack for 90 just isn't efficient enough for an EX. Just look at how much you can do with Keldeo EX with just 3 water energy attached to it (110 damage).