I can only assume that Nikon has done its calculations relating to stresses on the camera bayonet. I am also assuming also that it seems to be that Nikon only fit tripod collars on telephoto and zoom lenses weighing over about 1 kilo (2.2 pounds).
From the use of a lens on either tripod or monopod I personally like to have a collar, also for holding the camera while using a sling strap whilst walking. That is because I don't like the camera/lens swaying about. Of course, perhaps we have to look at it the other way around in that a D4 or D800/D700 + grip may be too heavy for the lens and camera bayonet.
After a closer look at the lens and taking into account the weight loss, which I am glad the lens has shed, I think it's daft for me to sell a perfectly good 70-200mm f2.8 VRI and buy an f4 version. I think I can put up with the extra weight.