True, if he stayed on his feet, we might not be discussing a broken ankle and torn knee. We could be discussing cracked ribs and a separated shoulder, instead.
What if a runner gets picked off at second and barrels his way to third and never stops- just runs through the hunched over 3B who is waiting for him, ball in mitt, and knees the 3B in the head (unintentionally)? I think there'd be an outrage, and, likely, one of those baseball riots where both teams run onto the field.
Why are things different at home plate?