A slide occurs when you hit the dirt before making contact with a player. Utley when straight at his knees without any attempt to hit the ground first. It was illegal and dirty.
The fact he didn't mean to hurt the guy is irrelevant. Repeating the same tired line......"good, hard slide"....."always been played like that", etc.....
There is a rule in place that should have been enforced, but the umpire was too incompetent to rule that way.
The new catcher rule is a good thing, sports have evolved. Targeting, diving at a QBs knees, NHL has updated rules, etc... all have been implemented for player safety. They don't compromise the integrity of the game at all if enforced properly. The Utley "slide"? Its been illegal for years, umpires need to enforce it.