This is just to see if anyone has any ideas about why Diamond Weapon attacked Midgar and why Meteor struck it. Post any ideas.
Personally I think it was because through out the entire game Shinra is the enemy of the planet. This is backed up by Diamond, Sapphire (Junon) and of course, Meteor. Surely if Sephiroth/Jenova was the real threat then the weapons would attack the Crater? By destroying Shinra the planet is saved.
This is only my opinion. Anyone else is welcome to suggest thier ideas.