Wishbone: I may have misunderstood the definition, but I don't think you can call it a hack n' slash when your only weapon is a laser rifle.
Still, a classic game, that I spent quite a lot of time with as a kid :-)
But, all You had in Barbarian was a sword.;P
I don't think hack n' slashes depend on the quantity of the armament.
Though, WoW would be more like "shoot n kill", but the basic principle remains the same. You, them, dungeon, death. Alien Breed might be a very nice example of the genre evolution here;)
Though, some say, HNS require the levels to be procedurally generated, and the story optional, but all in all, everything evolves... [but considering modern games] everything SHOULD evolve. Hence i'd say WoW is an early HNS in a different setting, now we argue laser rifles, why not argue spell casting, the were no spells in Rogue afaik. ;)