You can argue all you want, but they encompassed everything that is rock: A wild front man, speed/drinking habits among his band mates, massive shows, riot-inciting presence/exits, not to mention good hard rock with mild blues, punk, and metal infusions.
If you're a rock fan and you don't like G'nR, then you must alternately be a fan of pyschogenic/stoner bands, ie Led Zeppelin, Greatful Dead, etc. It's nearly impossible to love both types. The original G'nR was also the last great rock band. Everything since has been mere conformity to the system and current trends by comparison. The spirit of true rock is dying, and needs a G'nR reunion to revive it. An event like that would be in the running for the greatest show in the history of rock.