Pine tar strengthens the bat without adding appreciable weight. Batters sometimes get sawed-off by a pitch in on the hands and the bat breaks, even though they make contact, and they pop up to an infielder. A stronger bat won't break and the ball more often reaches the outfield. The George Brett pine tar incident wasn't a joke, the rule clearly states the limitation on how far up the bat the pine tar can be, I think 18. Brett's pine tar thickly covered the entire bat making it twice as strong as natural ash wood. They reinstated his home run even though the umps were right and he had used an illegal bat that day.
