It'd be nice if people were actually willing to listen to the reasons why decisions are made, rather than getting mad because they aren't decisions they like and refusing to listen to the people actually working on the software.
Particularly when it comes to #FOSS software, it'd be nice for people to appreciate the work that is done for free. Criticism is fine (and generally welcome), but being respectful towards the maintainers is important.
Things like this are demotivating, and just make me want to do something else with my life than work on open source projects.
I often wish I was more proactive in contributing to projects (even my own sometimes) than I actually am, and these kinds of attitudes are part of the problem.