“I promised nothing and I owe you nothing!” might seem harsh, small-minded and unnecessarily confrontational in the open source case. But in the greater context of Free software, it is the exact point of the license. The difference between Libre and Gratis has been stated so many times by the FSF and Stallman that I'm surprised it's even a topic of discussion any longer.
It's very much possible for users to have a great relationship with the maintainer/developer of their software, even without money. But by supporting a feature the user desires beyond comments/requests, financially, even a tiny, symbolic amount, the user can "buy" an incredibly amount of good will that goes so far beyond the typical user that the antagonism from maintainers against users will just melt away.
The obligations of the users and maintainers are indeed complex, that point I do agree with. But it is in general the users that fail to uphold their part of the equation, not the other way around.