Good question, and one that I am not specifically qualified to answer, but will cheerfully respond anyway. I suspect that many of the patents are for processes and techniques that educated and experienced engineers would consider logically obvious. If 10 engineers working on a problem would come up with essentially the same solution, then is it really a unique solution that is patentable?
Consider the notion of "pinch to zoom". Sure, Apple came up with it, but the technique is not really anything amazing and unique. IMO it shouldn't be patentable and is, therefore, silly.