Actually, the reason for serrated edges on coins was to prevent (or make visible) clipping or shaving the edges to remove some of the precious metal. This used to be common back when circulating coins actually had some intrinsic value due to their gold or silver content. The USA coins today are really tokens made of base metal and are not really "money" at all, so the reeded edges are there mostly to continue a historical practice.

Regarding the patent on the knurled chip, yes the patent disclosure should include some claim regarding the usefulness of the novel idea or process being disclosed. There is another kind of patent called a "design patent" which only provides protection regarding the appearance of an item, not its function. It's possible the chip design in question could be protected by a design patent since that may be the only purpose of the knurling. It would appear to this engineer that if the purpose was to make the chip easier to pick up, the grooves would run around the circumference of the chip, not perpendicular to its surfaces.