I'm the founder/CEO of Codeship and we got acquired by CloudBees earlier this year. And I want to make sure that Jenkins + all CloudBees products get better :)
Last year I was in contact with the Jenkins team and had a couple of meetings to discuss the things mentioned above and some more.
The developers where very nice and interested, I know they were doing their best but the problem was my problems where not top priority, and I saw some problems solved over the months but I completely lost my will to help when blue ocean started and Stage view was abandoned, the super dick move of restarting stages as well.
It was not a small deployment mind you, the system was a critical one (payments) with multiple sites and all the works, not a small license as well, I left that company but before leaving we were already migrating away.
We had a complete pipeline dependent on it, we were an early adopter of the whole JenkinsFile (A developer myself I pushed hard for it) and stage view even without being awesome was already part of our way of working. We wanted more features that I was already discussing and bugs fixed, out of the blue they change to a completely different thing that was pretty but didn't solve any of my old problems, and that will have it's own problems and was/is not even close to complete.
I just feel I wasted my time, I don't plan to make that mistake again.
But I hope Jenkins X can improve on the past mistakes and become a contender again.
Sorry to hear about those issues. I shared your feedback with a couple of people, and we will work hard on being more mindful when making such changes going forward.