On the other hand, litigation encourages innovation through design-arounds.
Aside from clear ownership of invention, it's also necessary to understand what is patented. Setting aside Microsoft's "we've patented this but we're not telling you which patents they are" there are cases like the "in-app purchase" patents that have absolutely no mention of purchasing in the claims (the claims are specifically about providing feedback to the developer through an app). Is buying a smurfberry "providing feedback"? I guess we'll have to wait for someone to spend a million bucks to fight it in court in order to find out.
Even when it's clear who owns the patent and how the patent applies, if you do a workaround you'll still likely find yourself on the other end of a C&D letter advising you that your app looks like it infringes their patent and if you don't settle now you'll face an expensive discovery process and have to hand over your source code to us to prove that your code doesn't do what the patent says it does. Not a big deal for OSS, but for proprietary software the prospect of handing over the family jewels to the competition isn't a good one.
And at the end of it all, after you've shown them your source code, shown them your workaround, shown them that you don't do what the patent says it does? They can pull the "Doctrine of Equivalents" card, and claim that despite the fact that the patent doesn't specifically name your workaround in the claims, it still applies. Enjoy your million dollar lawsuit.