in the modern world you don't need the ability to do a pull-up. You won't use it for work..

I would argue that you would use it for work, in that some of the same fitness indicators are used to evaluate people in the workplace as in the sexual marketplace. Things like posture, BMI, self-confidence, and even the number of sick days you take factor in. Even height is a fitness indicator. It has nothing to do with actual job performance, but statistically is an advantage. It is pretty much undisputed that fitness is related to health.

However, your point is valid and something I have noticed before. People get their motivations for fitness in different ways. I suspect it may have to do with extrinsic vs. intrinsic motivators?