Well, I don't think anyone would use averages to make decisions. "The average age for retirement is 62, and I'm 62, so I guess it's time for me to retire."
I think people are using averages (or medians) to compare. We're an early retirement forum, so we want to see how "early" we are, relative to most other people.
I'm actually a little less "early" than I thought I'd be. I'll be nearly 58 by the time I fully retire, and that's only a couple years early, relative to the average of 60. I prefer to use the median of 62 as a point of comparison, though, partly because it makes me feel better but also because I think median is a better measure than mean, in this case.