Isn't taking money for extra features in desktop software the oldest trick in the book?
Either way I don't think the problem is one of individual users not paying for their apps. I think the major problem is that of huge companies who get business value from the code use it to make money and give back nothing in return.
As proprietary software yes, but the moment you have something free with source code available, why should I pay you for it?
This is why most successful desktop open source desktop software, actually live from another sources of funding, but it hardly created the same changes as with developer tools.
Either way I don't think the problem is one of individual users not paying for their apps. I think the major problem is that of huge companies who get business value from the code use it to make money and give back nothing in return.