Pretty much as the title says. Why isn't it possible to build motors as microscopically and simply as they're built in humans? Why can't we recreate electronic nerves and muscles?
Human muscles take 9 months to grow and maybe 18 months to train for useful motions. It then takes years to refine precision and strength ... and still it falls short of an electric actuator arm in terms if holding power and precision ... but they last 80 years.
Robotic arms are optimized for ease of production, reliability, and strength. Biological arms are optimized for energy efficiency, among other things like being manufacuted from cells.
"elegance" is hard to define, but I think a Kuka beats a human arm in terms of simplicity, strength, and precision any day.