They absorb much of the impact on your back, legs, joints, and feet as they are flexible and act as a cushion. This will help prevent injuries, for both young and old.
Since clay courts are slower, it is harder to hit clear winners. You must stay in the point longer and try different shots to win rallies.
Clay courts are watered often and remain 20% cooler than a hard court. They also reduce glare from the sun compared to a dark hardcourt.