It is nice to have a lens that everyone admires and that famous photographers used, but I've never been able to convince myself that either the Cooke XV or the 250mm WF Ektar were worth what they bring these days. Certainly if the Cooke gets near a kilobuck the smart thing would be to put that money towards the new version in a modern synched shutter, and a 240mm Computar or Kowa plasmat performs as well as the WF ektar in a smaller and more modern shutter.
The lenses used by St. Ansel IMO bring far in excess of what they're really worth, and we forget that he and other photographers of historical note used a lot of lenses. Some of the pictures I admire most in "The Making of 40 Photographs" were made with a Dagor, and apparently a rather old uncoated one of "about 250mm". Maybe the Cooke and the WF Ektar are high dollar because they're identifiable; Ansel having mentioned them by name.
But another person mentioned that most photographers then, as now, used the best lenses they could afford at the time (pictoralists notwithstanding, then or now). I also suspect that once they had something decent in the focal lengths they wanted, they didn't think about it much anymore unless they had problems.
Steve