Because I love interacting with balloons in general, and once a balloon pops there's not much you can do with the scraps.
not popping the balloon = more fun
It's more like if you squeeze the balloon too hard, the neck will bulge out too far and get snagged on the clip (which can easily pop the balloon).
Also, if the clip isn't on the balloon properly, it can shoot off the balloon when you squeeze it.