I see one problem with this - for outside contributors. If I contribute a patch to a project that is free of charge, then my contribution is on the same altruis

I see one problem with this - for outside contributors. If I contribute a patch to a project that is free of charge, then my contribution is on the same altruistic grounds as other devs' contributions - for both of us the profit from our contributions is the continued existence and improvement of the software. However, if an organisation is charging money in some way, then I do not profit equally - I get better software, but the organisation gets both better software and money, which they pay to their staff developers. That is, my contribution has calculable monetary value and someone else gets paid for it. Obviously for small contributions, e.g. writing or updating a bug report, or fixing some trivial one-line bug, the amount is insignificant and not worth thinking about. I'm thinking more about larger contributions - extra features, tricky bugs, etc - stuff that takes weeks or months to develop. You can expect outside contributors to want some guarantee of getting paid for large contributions if you're a project that is actively monetised in some way, even if the software is also available completely for free.