The fact is, it's just bad business not to patent software as a defensive measure against competition, at least when you make enough money for the people with patents to sue you first. This doesn't mean anyone likes being in that position: I think some of them, at least, would appreciate being able to implement competing technologies without licensing them.

Yes, I'm well aware that defense is a reason for patenting things. I think it gets much easier to see that as the primary reason for doing so when the companies which do it the most also work to reduce (as opposed to increasing or exercising) the offensive power of patents.