An interesting thread. I know that when it comes to competition, the search for a competitive edge, legal or not, has always taken place.
But if it is that common, then why continue to hide it? An illegal edge that is unenforced or ignored has become, in effect, a legal edge. So, limit the rules to just the state of the game itself - having a pitch clock, use of a double bag at first, setting rules for where players can line up in a "shift," and the like. Then, let pitchers find their favorite grip enhancement substance (or even the old "spit ball" type of substances that effect a ball's flight), but also let batters use performance enhancing drugs and juice up their bats.
Of course, someone will ultimately pay the greatest price - an enhanced spin rate 95+ thrown ball will be batted back as a120 mile an hour velocity, hit right back at the mound and hit a pitcher. If he's lucky, it will just break a limb. If he is unlucky, a head shot will kill him.
Either rules mean something and have a purpose, or they do not. If the quality of competition regardless of means is more important than guaranteeing some form of fairness and safety, then open it up for both pitchers and batters. If natural ability or learned techniques are to mean more than chemical substances and performance enhancing drugs; or lowering the risk of someone eventually paying too high a price is important - then random checks and random drug testing may be required to quell the temptation to seek that "edge."