I think it's best left to the software developers to decide the licensing terms for what they develop.
Personally I use both proprietary and free software. I don't really care whether the software is free or whether it costs $200. I just select the best available if it's within my budget.
I use WordPress (free) for the blog because it's the best blogging software available for my needs. I use VBulletin (proprietary) for the forums because no free software can compete with it -- the price is irrelevant. I use NetCaptor (proprietary) for my primary web browser because I find it more efficient than either Firefox or IE. If Firefox was better for me, I'd use it.
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