If you required patent owners to make actual products it would actually hurt the little fellow since he's got to either spend lots of money to build the darn thing and try to sell it or lose the patent. Making the darn thing and trying to sell it is expensive. Selling or licensing the patent is much more do-able. Also, a lot of patents make use of other patents, so if XYZ Inc. holds the patent for a certain type of levitation device and you figure out how to make it operate 100x more efficiently and patent that, go to XYZ Inc. and say "hey! Look what I got! You wanna license it?" they say "Oh, but you're not making a product with it so we'll file a complaint with the USPTO, wait a week, and use the idea to make our levitron better anyway! hahahaha!"