But there's one huge problem: pinball actively encourages boring play. In almost all circumstances the correct play is slow and cautious. There's rarely any time limit so you want to trap the ball whenever possible and make every shot from a complete stop. Even with timed modes you don't want to rush because the risk of losing the ball is too great. Multiball is best played as a succession of single balls. I had more fun as a beginner because I was more often forced to react to unexpected events.
This could be solved by adding a sensor and solenoid at the base of each flipper to kick the ball out if it detects you holding it (there are other uses for holding the flippers up, eg. drop catches, so just preventing that in software would reduce the skill ceiling). The flipper size could be increased to compensate for the increase in difficulty. I think this would be good for the game in the long run, but it will never be accepted because it would hurt the rankings of the best players, and their support is essential for the industry's continued survival.