Simple - BLU wasn't designed with the express purpose of conforming to a single role, but instead drawing from all of them whilst making it a DPS-centric class.

I would at least say that BLU is evidence that they can do something more interesting and complex with healers without overwhelming the more casual players - IMO, most players are not as bad as they were in Heavensward, so it would be nice.

If for no other reason than to give those players a little more something to do between healing.