Insisting that sliding runners must hit the ground before the bag is the one clarification to the rules that should in certain instances save some injury. Even the clarification about sliding past the bag won't save anything. Think about it. If the runner slides past the bag, he has missed hitting the infielder. That particular infielder is standing there tagging him out as he goes past.
The rest was a consequence of umpires not enforcing the existing rules.
Umpires would not enforce the rules about a base runner's path to the bag. They simply would not do it. The result of that was runners chasing 2nd basemen almost to the infield grass and chasing Shortstops almost to the OF grass the other way. This filtered all the way down to high level organized scholastic and other ball where either me or my Shortstop got chased one way or the other by runners constantly. There is nothing out there away from the bag but flesh and blood infielders. So where were these baserunners going? Its not like baseball lined up two extra, auxiliary bags left and right of 2nd base for runners. So instead of enforcing the rules they had, we got the phantom out at 2nd. Baseball logic at its best (ie. two wrongs make a right):
A) We won't enforce the rules we have and make calls
We will screw up another rule because of the call we won't make and thus make another call in error
Slo-mo replay forced the umpires to their knees on this one. They were forced to pay attention to the fielder's position as he took the ball to turn the DP. Slo-mo meant the umps would be caught not paying attention to the fielder's positioning as he attempted to turn the DP and that made a huge dif at the ML level and frankly has meant a marked improvement at all levels which of course supports the idea that the umps could actually see if the fielder had the bag and the ball at the same time a very high percentage of the time. Its not every class of baseball that has slo-mo.
So forcing runners to hit the ground before they hit the bag is really the only change of all of those made that might save infielders. The rest is all clap trap that has had the effect of making fielders "feel" safer when in fact they are not. Pedey is right about the effect on infield play. It has encouraged infielders to sloppy footwork around 2nd base with fielders feeling like they are protected by a rule. FAT CHANCE!
Frankly, the only thing that has actually changed the number of injuries around the bag is the head first slide. Now its runners getting injured at a higher rate than they used to be injured. But looking at foot first slides around the bag, frankly I don't see a difference. I see at least a spiked infielder about once in 20 games and given how many head first slides there are, that seems about right to me. A spiked infielder is really about one inch from an infielder with a broken ankle or damaged knee. So I am not convinced much of anything has changed that would not be attributed to the head first slide.