Can you tell me class-defining rotational/combat characteristic of Mages?
I don’t know why you would seemingly pretend that Lone Wolf or access to melee spenders would somehow rob Hunters of an identity, or that they should be uniquely capable of being described across the whole class by characteristics beyond the obvious (access to pets, traps, and high relative mobility).
Mages (shared access to Blink, Popsicle Form), Warlocks (Shadowbolt and Corruption but probably not really), Warriors (Rage, Shouts, Charges, and Spell Reflect), etc., are no more readily or simply describable in terms of their class characteristics across the whole spec. Nor do they get aneurysms over Whirlwind, Fire Blast, Corruption, Shadowbolt, etc., all playing totally different within each spec.
It is both precedented and fine for one spec’s version of something to have a bonus feature baseline. It’s fine for Countershot to become Muzzle (9s shorter CD) or Arcane Shot to become Raptor Strike (10 less Focus) from melee range, etc. And it is fine for Kill Command to be a spender in one spec and a builder in another (just as, say, Execute is for Warrior). Those are not problems. We can prefer a Kill Command-less Survival, sure, but its place makes sense, is not an issue, and certainly does not make the class incoherent.
Tl;Dr: I do not understand your implication that every hunter spec must use a pet and be ranged to be a “Hunter”, especially given that you’d faulted Kill Command just for existing across multiple specs.
That level of self-similarity holds for no other class. Not every DK makes heavy use of pets, nor Frost, not shadow magic. Not every Warrior has multiple rage spenders or mainstay builders. Not every Mage has simulcast or ramped damage. Not every Warlock actually cares to maintain as many DoTs as possible. Not every DH has significant access to Sigils, nor will they build or spend in the same way.
Hunter specs need not all be ranged, castless, and pet-using. It would be entirely fine for every spec but BM to choose—actually choose—whether they want to have a pet and every spec but MM to choose whether they want any casts and/or any compensatory advantages from/when playing in melee range.