a softball with a 16-inch diameter ball would really be unbelievable. A basketball is less than 10 inches, so imagine something ~2x the size of a basketball being swung at with a bat.
if that was the only difference. the fact the ball is designed to get softer the longer it is played makes it so hits at the start of a game are different than at the end. fielders would learn this and change tactics based on that. normally, when the ball goes flat during a game, it is replaced. that in and of itself made it interesting to me as a standout feature.
A softball like 10% bigger isn't that interesting.