@tsrberry @joepie91 @baldur if you're operating at a larger scale (especially on gui tools) then running annual community feedback campaigns is a huge winner. make it a simple survey form - minimum friction, maximum response rate. people will tell you all the things that have been bugging them but never got around to opening an issue for. commonalities in responses will help you direct your efforts and make a lot of users happy with relatively low effort.
@tsrberry @joepie91 @baldur but ultimately at that scale you need input from actual designers - people who really know how to make a good UI/UX, and who can tell you what you can do better. that can be direct, by getting designers to come help with the project and help come up with better approaches and workflows, or it can be indirect feedback. and be humble. don't get defensive because you're attached to the project or it'll be work to fix the issues. it's hard work to do it right!