We agree that the open source ecosystem is incentive-driven - most actual code contributions are made due to simple economic incentives (though not nearly as simple as you make out, but that's a whole different discussion). So, approaching things from this angle, I would say that although most people are simple rational actors who contribute code because they stand to benefit directly, someone has to take a larger view, and try to make sure that impediments that gum up the free operation of this incentive system are removed. The intellectual property trap is just such an impediment, and the people who bother to take the long-term view are the ideologues.

I say again: we need both. I for one hope that the argument between ideologues and pragmatists is never decisively settled in either's favour.