Its not only more pure its much faster, if the numbers I found were right by free-soloing el cap Alex Honnold beat his previous speed climing record by 16h (20 to 4h). I'm guessing if removing a helmet increased the speed by 5x many daredevil race car drivers might consider it, its not exactly a safe hobby to start with.

source: http://www.yosemitebigwall.com/speed-climbing