The variable gravity thing is an interesting point, I still wonder if forcing out that volume of air would have been sufficient. When the doors opened there was a shuttle parked near the entrance, it would have been cool to see it flung out as the gravity flipped ninety degrees.
IIRC in the various official tech manuals the gravity generators were in the floor decking, they have been shown to fail. be reduced or be turned off. As far as I now they have never been shown to either flip the fields at right angles or even cascade a wave- tractor beams have always been shown to move objects in the shuttlebays or near the ship. When the bridge crew was debating different ways to avoid the collision it was only mentioned to open the doors and let the air push the ship, Data pushed a couple of controls and it was so. Re configuring the gravity generators to increase the velocity of the air moving should have required at least a mention and some more beeps I would think.
Besides, while the internal volume of the unseen main shuttlebay is large, I think even if they expelled the available air at the highest possible speed and even tossed out every shuttle stowed there it still would not move the ship of that mass much.