I didn't know they consider it a pro lens. I don't. The image borders and corners show less resolution wide open than should be from a lens in this price range, and the same is true with sharpness in general past 90mm. Its distortion is rather pronounced except at mid range focal lengths and vignetting is on the high side. Optically, the lens just isn't good enough for me to consider it pro, but that's me.
I've seen ugly photos due to lessor quality lenses on the D3X. I didn't say, by the way, that you can't use consumer lenses on the D800, only that in my opinion, they won't work so well. That being said, I don't think you necessarily need pro lenses, as an awful lot of the "pro" definition is the speed of the lens, which has nothing to do with optical quality. It's the optical quality which is important with the D800, and there are some consumer lenses which have solid optical quality.
Here's the thing, a lot of this is nitpicking, and a lot of this is what output is used for displaying the photo.
For example, the AF-S NIKKOR 14-24mm f/2.8G ED is a pro lens which many absolutely love. I don't like it for a variety of reasons. I can't put a polarizing filter on it, and I don't like its distortion at its low end, and especially the flaring when you use the lens. After carefully reviewing and testing that lens, and the "less capable" AF-S NIKKOR 16-35mm f/4G ED VR, which is a pro lens, I opted for the 16-35mm. I found it was more suited to my work. It turns out the distortion differences are there, but actually trivial, in my opinion. The lens flaring though is different, and I find the VR more useful than the f/stop I'm giving away. Regardless, the differences here are generally nitpicking (not the flaring).
In addition, I've seen photos displayed on computer screens which were taken with the D7000 and "cheap" DX lenses, look great, but print them out on A3 paper (13"x19"), which is my primary print size for showing off my photos to clients for travel brochures, for example, and they look lousy. Part of the problem with the "cheap" DX lenses is often they are less sharp outside the center of the photo, especially at the edges. Much of that goes away with "cheap" FX lenses on DX cameras, as their soft edges aren't captured by the sensor. Soft edges can kill a great shot.
That being said, I don't think anyone can argue that the quality of a lens optics makes a difference in the quality of the image, and in my opinion, the more MPs you have in your sensor, the more the quality of the lens will count in having a great shot, or one that's just okay.