Ball point needles get dull too. Fabric is tougher stuff than it's given credit for, and it's rough on needles.
They also don't work well on tightly woven goods. On knits, where the yarns have inherent mobility because of how the fabric is formed, they can displace yarns, and not cut through them. On woven goods, there's less mobility in yarns, and the needle will penetrate by forcing its way through. With a sharp point, it cuts the yarn; with a dull (or ball) point it breaks them. Try a sharp (that's a style of needle point) needle, you may well be presently surprised at how well it works.
@Roger: The big advances in needles since WWII have been in specialized point shapes for specialized purpose, and in the coating/plating they get. Decent needles are chrome plated, which reduces the wear they get and reduces the operating temperature. Better needles have TiN or similar coating, which is even better. There are other coatings in use, too.
But really, buy yourself a christmas present, and change the needle. You'll notice the difference.