well, having a fireball critting for 6M isn't a big deal..,
having 5 fireballs, a few mind blasts and chaos bolts and a thousand auto attacks all in the neighborhood of 6 million, isn't an especially optimum situation
then on the other end... every monster, bad guy and boss doing that as incoming damage... which the fearless raiders are taking... which the fearless raid healers have to heal
and that's one raid
think about all of that with x numbers of raids going on at any one time...
all of that math is strain on the servers, not to mention everyone's computers which boosts minimum system requirements and reduces effect of eye candy and effects without computer upgrades
smaller numbers with less meaningless 0's would be better for everyone
what would be nice, would be a separate number system that shrinks itself down when fighting Skull bosses
like use the mega damage model, only when really needed... on the toughest fights with the most players involved
... also maybe in pvp when there's 80 of the highest geared players running around on a fairly small map where the action is completely unscripted