The dependency on telemetry instead of actually sitting down with a user and watching them use your software is part of the problem. No amount of screen captures, heatmaps or abandoned workflow metrics will show you the expression on a person's face.
You actually skipped over the most important part:
> You can and will happily do things your users/customers hate if ... you dont have to face their criticisms directly.
A lot of software developers can't take criticism well when it comes to their pet projects. The entire FreeCAD community, for instance, is based entirely around the idea that FreeCAD is fine and the people criticising it are wrong and have an axe to grind, when that is exactly backwards.
Which is also why UI/UX on open source projects are generally going to suck.
There's certainly no money to pay for that kind of experiment.
And if you include telemetry, people lose their goddamn minds, assuming the open source author isn't morally against it to begin with.
The result is you're just getting the author's intuitive guesswork about UI/UX design, by someone who is likely more of a coder than a design person.