1) Wrist supports. These should only used as a training aid and not allowed in sanctioned competition. Unfair to those who actually have strong wrists and hands.
2) High tech bowling shoes. Unfair to those who can't afford them.
3) The use of throwing a reverse hook. (Backup ball) Unfair that these people have the option to use the other side of the lane if they choose. (Like Robert Smith when he won the Japan Cup.)
4) Excessive ball speed. Everyone should roll the ball at 25 mph or less. (Not everyone is a freak of nature fireballer like Eugene McCune). Those of us that roll at a 'normal' speed are at a disadvantage.
5) Any ball that thumps over the thumbhole on spare shots should be declared illegal. Not everyone can roll the ball end over end and not miss a single-pin spare in over two seasons like Walter Ray.
6) Any backswing that goes over the bowlers head should be declared illegal. Most of us would dislocate our shoulders trying that.
So, everyone should use their thumb, wear house shoes, and gently stroke the ball up the 2nd arrow. Have fun!