People claim that Jenova didn't arrive on a meteor, I personally don't see how that could be possible.
Given that the weapons don't even attempt to attack meteor, scale isn't that important. However considering the length of time the planer has been healing, that is a pretty damn big crater. Meteor wouldn't be able to do much more damage without completely destroying the planet. This would (unless one of Raistlin's idea's in another thread is true) completely defeat the point.