Interesting point. However, in my Alpine climbing days a few (ok, a lot) years back I did not really notice the altitude (IIRC the highest climb I did was the Iseran). What really got me were the descents, and how you were constantly risking your life no matter how careful you were.
Of course, we were riding tubulars then and always terrorised of melting the glue and having the tubular slide on the rim...