I might agree with this, but considering how much easier Ghost EMP rounds are to handle and how much more accessible they are, protoss could certainly use a way to go into more engagements with full health, like most terran engagements (due to the speed of medivac and SCV healing). Zerg units heal (and are worth much less) and as mentioned before, terrans heal even faster than zerg, but protoss normally go into late-game battles with sub-optimal health values (especially if the protoss player was well harassed) and building raids are more effective if you pull out and come back again (against terran, they repair, zerg heals, but protoss buildings are left with lower health with just shields recharging).