A rule change would include interpretation of said rule (another way for ump to interject themselves into the game). There is already a rule. It is not enforced now, so how will adding a new rule help?
Good point. So did pointing to the strike zone rules to umpires improve the game or retract from it? For years, the American League was known as the high strike zone league and the National League the low strike zone league. Some say it was because both American League and National League umpires were segregated at one time and the American League umpires used giant foam pillows as chest protectors. The low strike was hard to call because, simply put, they could not squat as easily as a National League umpire.
So over time, American League umpires, even without the giant heart shaped foam pad, just basically *developed* their own strike zone. And thus, the American League umpires just basically ignored the low strike for many a year and with the advent of the DH rule, the game became a farce. Yes, I said it, a farce. So the league didn't change the strikezone rules, they did other things:
1. No more American League and National League umpires... it was MLB Umpires... period
2. Re-introduce the strikezone rules to all umpires
3. Evaluate umpires on strikezone calls
It changed the game for the better, but it wasn't because they changed the strikezone rules, they changed the periphery surrounding the rule.