The bait and switch is because people feel the social contract has been broken. If you start a project, invite people to come along and donate their free time

The bait and switch is because people feel the social contract has been broken. If you start a project, invite people to come along and donate their free time to making it better, building (and benefitting from) a community of people working towards a common goal, suddenly switching that project to proprietary is a bit of a dick move. Sure, it's legal, but for the people who thought they were collaborating together on something it feels a bit crappy.