I guess as a non programmer that buys software I am always shocked when programmers advocate that useful software shouldn't have a price.
Many people believe [...] that you should not charge money for distributing copies of software, or that you should charge as little as possible — just enough to cover the cost. This is a misunderstanding. Actually, we encourage people who redistribute free software to charge as much as they wish or can.
In other words, it is important to distinguish paid software from proprietary software, otherwise the situation and arguments become confusing, indeed.
However, I'm sure the same people will happily spend $100 for a book that teaches some open-source tool. Or at least they would never complain that there's a price for it.
Why?
At the moment we seem stuck in the middle of this transition and you either pay for a locked down copy or you get the Free copy for free. But Kickstarter seems like it's getting mainstream so the concept of paying in advance for something that is built to the specifications of the user may at last become common in software.