[trhway]

>Perhaps it works because of the expense of determining which patent claims could realistically survive a motion to dismiss, i.e., the hourly rate of the patent lawyers hired to do this analysis and the number of hours they take to do it.

or may be because a patent court case is more like rolling a dice with very significant potential damage. Business likes predictability - license is just a static cost to be factored into the price of the product - vs. high risk gamble. And software patents i think are worst of the worst in that regard (nevermind that i have several of them myself :).