Grew up near New York City then ran in Miami for 36 years, almost all on pavement (very little grass in Miami for running). Result of decades of high mileage on pavement: left hip replaced in 2005 and right hip replaced a few weeks ago. The two guys I ran with the most - also high mileage - are similarly crippled up and also had to stop running years ago.
Running on grass is easier on the joints AND it does more to strengthen the muscles. Pavement is faster than grass - thus road 10Ks are faster than Cross Country 10Ks. Your legs work harder to push off grass than they do off pavement. Distance runners, especially Cross Country racers, should train as much as possible on grass and other soft surfaces.