I think it is always good to try to look at things from a different perspective, so please bear with me when I make this argument against Open Source and pro Software Patents. It is just an argument.
Back the old days, the Software Ecosystem didn't need patents. Development of software was hard and relatively expensive, so the only way to make headway in the marketplace was to come out with products that were in some sense better than what there was before. Software more or less competed on innovation. Sure, some companies were better at this than others and sometimes innovation was more making things better integrated (Notably Office & Windows) and sure there were some companies that tried to compete on price by coming out with cheaper products and lesser features but they never got anywhere really; cheap is not free, plus they just didn't have the PR to convince people to go with there.
Then along came the Free Software movement. They did not just bring a PR machine that trumped Microsofts along, they also ferfently started copying functionality of the commercially available software. The PR machine would on the one hand point out as much as possible that Microsoft never innovated, while at the same time copying whatever Microsoft build in Windows and in the case of Linux, starting with an effort to copy more or less Unix; indeed the whole thing reminds me of the Soviet Union which in its propaganda would claim that the United States were a terrible place, with suppression of the common man, unemployment and widespread poverty, while at the same time putting up as a 5 year plan to overtake the United States.
In the ecosystem of Software, this was new. Suddenly there was a respected (because of the PR machine) entity writing software for free. The old implicit deal of the industry whereby you could copy innovations of others since the marketleaders would be compensated for their efforts anyway, suddenly stopped functioning. Viewed in this way, Software Patents are just a counterfailing power, a way to protect the innovaters from the Free.