Again, if you cannot see why comparing a healer to a dps is fundamentally wrong when talking about mechanics and spec specifics, i cannot really help you understand why being forced into melee range as a ranged dps is an entire different thing then having a nova spell that deals only damage on a healer.
You have to consider that all other examples are situational and nonmandatory, while AE is the only option an entire dps spec has to execute its intended AoE rotation.
And again, if you cannot see why forcing a class that represents the archetypal wizard type character (staff, robe, pointy hat, generally old and phisically weak) to fight next to his ironclad, massive and phisically trained brutes or his nimble, extremely agile and again combat trained partners goes against pretty much all logic, it's pointless to discuss it further.
In some lore combat mages do exists, but nowhere in the Arcane school of magic of WoW it is stated that they are prone to self suicide (like you suggested at some point) nor risk takers, nor combat trained, nothing. Actually, Arcane is the fundamental school of magic, and all other schools are actually stemming from Arcane. So, if anything, Arcane is even more archetypal, favouring intellect and reasoning above all else (mastery is called Savant, not Magical Warrior).
I quoted both class fantasy and mechanical arguments, and both are perfectly valid.