Fair enough, but health and fitness are not just for sport and culture. It's practical; you don't want your astronauts to have medical emergencies in space. Similarly, if you put resources into training them you'd rather they didn't die at 30 due to poor genetics.

If any new tech threatens to render the premise obsolete, it's robotics. Not sending humans to space in the first place avoids the issue of selecting astronauts at all.