I have to disagree. The only time that I have an issue with this is when I am trying to finish up a particular brand of ball. I can play a quick blitz game to finish it off if necessary and get it out of the bag.
You are prompted when you start a round of this being the last ball of this type in your bag, that should be enough to make you buy more balls or just choose to play out the one that you have. I would much prefer WGT to work on other problems rather than fix something that already works and really is a non issue.