"Sephiroth was the one summoning meteor. I think he'd be a good target."

Kishi and I have stated numerous times that the Weapons were not intelligent. They wouldn't be able to make any connection.

"The planet has been hit before by meteor, it knows what it's like."

When? Unless you mean the pictures in the Temple of the Ancients. But, if so, where's the big-ass Crater it'd leave, even if Life started over?

"Are you suggesting the planet just created them, then when meteor turns up, "Go! Charge! Attack! Oh... right, I didn't give you the ability to do what your designed for... Tell ya what, go attack them people over there and hope noone noticed.....""

No, they have ability. They are awesome killing machines, capable of destroying almost anything. They are random killing machines. When the Weapons are unleashed, there's three possibilities:

1. The Weapons fail. The crisis wins, and the Planet is destroyed. Worst possibility.
2. The Weapons destroy the crisis right off the bat, and then go back to sleep. Best possibility.
3. The Weapons destroy the crisis, but in the process kill off most/all life. Life starts over. This is somewhere in the middle.

The Planet is just preferring #3 over the crisis winning.