You are confusing Free Software [1] with Gratis Software. Free Software usually does have a price, although not a price per license. Here's an official statement [2] from the GNU project:
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.
There's a nasty double standard here - just because it's "software", people seem to be complaining that it's not free.
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.
If I had the choice I'd rather spend $20 bucks on a wiki or website that was CC licensed so that it could be updated and improved without reliance on one individual. Same for software.
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.
Books are physical things, programs are not. Physical things are often thought to have more intrinsic value than virtual things because the money was transformed into something you can touch and feel versus a vague collection of bits somewhere on your gargantuan hard drive.
