It should 100% be this way...
Unfortunately, WGT would then not be screwing you over and forcing you to buy multiple packs of different balls just to be able to use the previous ones. After all, their aim is to squeeze every last buck out of you. That is why you have avatars, drinks and clothes popping up instead of new courses, or improvements to the actual game play.
It is a great game, but just dont expect to get great value or bang for your buck.