Don't you think that's an overreaction?
@Gravikor
1) No every Mage will play with Gravikor, because most of them have to pay 4 Spellpoints.
2) Gravikor only makes sense, if there are at least 2 Flyers on the field. btw. Your own Flyers are affected too.
3) Flyers are not dead because you place Gravikor, you still need to kill them. But, you just spend 8 mana for Gravikor, that could also have been a creature to protect your mage or attack your enemy.
4) Some Flyers are strong, even if they don't fly (Guardian Angel, Legendary Angels)
@Sandstorm
4 Dice against Flyers is not too scary. Ring of Fire (5 Dice) or Electrify (Stun) is a greater threat. But if you are still worried, just avoid moving your Flyers in one zone, problem solved.