It seems to me that the idea of carrying air tools on the trail was the new "in" thing to do. (Exception to Bob and folks chasing racers and whatnot - I am referring to the regular guys who wheeled trails on the weekends.) There was probably an article in a magazine, and everyone thought it was a good idea, and wanted to replicate it - much like so much overlanding stuff today.
Not to knock the idea, because there are some valid reasons to carry air tools. But, what I think most people did not realize at the time was all the extra weight you ended up carrying. Which required more suspension, which required more .... Not to mention, heavier trucks broke more frequently. Which required trail fixes - which were made easier by using air tools......