When the reference was made in the OP to not wanting to stop and have to restock the PP in the middle of a round I took that to mean being able to make sure the bag was stocked properly BEFORE the round. Same way we can see how many of a ball are left before we tee off.
You are right that the PP does indicate how many hits are left on it when it's on the screen during the game. I don't think much more is necessary beyond that while the game is being played. All it takes is a cursory glance at the PP on any given putt in the game to see what's left. Having a warning pop up during the game as you were reading it still forces the player to interrupt play to buy more, something that he indicated he wanted to avoid. Only way to avoid that is to know what's left BEFORE the round and we shouldn't have to jump through hoops to find out.