Maybe this is crazy but you could listen to them, treat their comments as valid, give a clear indication that you understand what they are saying, and then seriously consider their concerns? Too often I see people shut down and go into a kind of "you can't tell me what to do" coma and lash out. That doesn't solve anything.
Ultimately, most of these maintainers are volunteers doing what they're doing in their spare time out of love for their craft, and they have no social or professional obligation to let other people dictate the direction of their project. The nice thing about open source is that if there is a critical mass of users who are unsatisfied with the state of the world, they can fork it and take it in the direction that they want. Yes, "just fork it" is often used as a cliched excuse for shutting down conflicting viewpoints, but it's such an effective excuse because it's also a true statement.
What if there isn't a critical mass? What if there's an important project which has received and ignored perfectly reasonable user requests, or even patches that "just have to be merged", but there's no critical mass for forking? Sadly, that's how pretty much everything else in the world works as well. Like democracy and capitalism, it's the worst system in the world except for every other one. Everybody has a laundry list of complaints about their most-used software, and has thought to themselves, "if only they would change this one thing", "if only they would just merge my patch", "if only they would listen to me", then everything would be great. What the "if only's" of the world don't see is that for every popular project, there are dozens if not hundreds or thousands or millions of people who each have their own "if only" which in many cases are contradictory if not outright wrong. If someone just doesn't have time to work on their passion project and drink from that firehose at the same time, I do not judge them for choosing to focus on their own code.