It's how the US patent system works. Basically it's almost like copyright: you can patent virtually anything that hasn't been patented yet until challenged in court as either trivial or not original (i.e. prior art exists). Essentially the US patent system achieves two goals: shift the burden of verifications and validations to competitors and courts; and secondly, provide the US some advantage on the international level via the Patent Cooperation Treaty. Any crappy patent may turn out to be important, so just let them register everything and see which one "sticks".