Pitch framing, instant replay, the height of the mound, left handed vs. right handed first basemen are all little nuances. A catcher hustles down the first base line to backup infield throws and how often does it happen that he saves the day? An intentional walk becomes a disaster as the pitcher lobs the ball over the catcher...happen often? Little things.
First batter up, first pitch, umpire calls it a strike, while the announcers and the bench groan because it was a foot outside. Important blown call? Probably not.
Bases loaded, 9th inning, 3-2 count, down by a run, same call. This time vitally important.
Pitch framing's importance is dependent on game situation. Greg Maddux seemed to think it was important. So did Steve Carlton. Didn't help them on every pitch, but it did on critical crucial pitches.