Certainly there's snobbery associated with large format acquisition, particularly if the print isn't done digitally. The more the print cost to make and the more difficult it is to reproduce, the more perceived value there is in it. That said, the best prints that I've seen were optically enlarged from 8x10 film, so there are aesthetic reasons, too, for their value. Good digital prints look pretty close, though, up to any reasonable size.
The comparison you posted is a little unfair. 120mm is quite long on 645 whereas 180mm on 4x5 is a "normal" lens. Longer lenses are typically sharper across the frame (look at the mtf data for Canon's telephoto l primes: so good!). This is why the comparison between the 150mm rodenstock and the 80mm distagon is unfair if you look at the same image circle, as I mentioned, and why I then compared a 40mm image circle with an 80mm one to be fair.
And in terms of equivalent focal length, this http://www.s.leica-camera.com/summarit-s-1-2-5-70-mm-asph-cs/
would be closer to the 180mm Schneider. Not nearly as sharp as the 120mm. While the Schneider still does extremely badly in comparison at 20lp/mm, the sensor is three times larger in any dimension, so it only has to do a third as well to deliver equivalent sharpness across the frame. And its mtf curves go on to 100mm, but the image circle is only 80mm without lens movements, and within that range it's not so bad at all. Pretty comparable to, if slightly worse than, the Leica when surface area is taken into account, obviously much worse over the same surface area, though.
I'm not saying you could mount a large format lens on a dSLR and expect good results (although I've tried it and it's not so bad as you'd think), just that the criteria are different for large format and digital lenses. A large format lens has to cover a huge area; it's not going to be as fast or as sharp across it as a $5,000 leica lens covering a small sensor, but it's not designed to be and doesn't have to be to get equal performance overall. The tolerances involved in shooting large format are also quite poor so it's almost not worth it spending money to get a perfect lens. The flip side of that is you can do lens movements pretty dramatically in the field using the ground glass and a loupe for focusing and get good results consistently because the film plane is so big it's easier to manipulate. Using lens movements on a smaller sensor is way harder.
Anyhow, the moral of these mtf charts is I'm glad I bought the rodenstock lenses! And yes, they are intended for use with 4x5 film and I wouldn't trust them near a medium format back. I also couldn't afford a medium format back, conveniently. I looked at mtf charts, too, and was pretty distraught by them, but using the actual lenses impresses, and when you think about the whole system rather than "why is this not 16 times better than 135" it makes sense.