There are so many factors that make a lens desirable or not, and quite a few of these are not easily quantifiable. It's not only about AF speed, resolution and contrast. The $4000 58mm Zeiss Otus is a manual focus lens, and tests poorly. But there isn't a lens near the focal length that I would rather use - it is absolutely three-dimensional. You just can't measure that. The new $1700 58mm Nikon lens, also tests poorly due to its not being a flat field lens, but produces an image that is superior to the competition in that range. Each lens needs to be considered on its own merits, be it a prime or a zoom. I have seen some pretty awful prime lenses. In the Nikon stable there are these questionable efforts from the Nikon lens designers - all primes:

15mm F5.6
18mm F2.8
20mm F4
28mm F2.8
85mm F2
105mm F4
135mm F2
200mm F4
300mm F4 ED-IF (poor tripod collar causes lots of vibration)
300 F4.5
45mmF2.8 GN
200mm F5.6 micro nikkor

These are all primes that are/were borderline turkeys.