I never pay attention to it, but does defeating the computer that controls the robots offer an XP reward? It doesn't do damage, but it directly controls the robots that are doing damage to you. I feel the same way about portals that summon rikti or demons; if we don't get XP for the summoned critters, we should at least get something for the thing that summons them.
As for the healers, I have to agree with the sentiment that they are increasing the risk by healing other mobs that wouldn't buff themselves. You should get a nominal XP reward for such things. As for the DE emanators, those are dropped by certain DE critters themselves, so technically acting like a toggle power and the XP value of the critters that drop them should have that factored into them already. But Surgeons are free roaming critters.