I'm still unsure of what it is, thought I had an idea but...
I'm guessing that the term "PIP" is what WGT call the dots on the green. So, my thought was.... if you had the putting grid on, during the down swing the pips(dots) would still appear and still in motion, IIRC that's how it was before. Didn't they (wgt) change it to where the dots would just freeze (but remain on screen) during the putt???
My guess for the PIP animation was this, in stead of them freezing in place during the downswing of a putt, they would remain in motion as long as you had the PIP animation toggled "ON". But with it toggled off, the pips would remain but only frozen in place.
I was just testing this and realized that the dots continued to move during the downswing both with the PIP animation turned on and off. But, with the putting grid selected off, the dots/pips and green grid disappears completely as soon as you take your backswing.
I did find that with the grid toggled on, that the speed of the dots did speed up on the downswing of the putt.
My guess, the PIP animation is not working.
My thoughts on how they'd be useful... Those who are 'miss-ding' putters, continued movement of the dots would help to remember which side of the ding to miss and by how much. For ding style putters, once you have your aim lined up and know how much power to hit your putt, the dots aren't as necessary.