I totally agree. I love and hate Nix every day that I use it. I hope that someday they'll make it more user friendly, but I suspect it'll be someone else with a new approach.
I struggle to see how another tool will take the spot. I think the power of Nix is that the underpinnings are so pure, academic and well thought out that you can rethink package management in a much cleaner and sane way. Unfortunately that results in the UI not being the priority, though I think the opposite approach results in a conventional package manager with their many flaws and trade offs.
I generally think the UI first approach is a better way of building tools, but there are special cases where it doesn’t work due to their being so many edge cases that you need pure underpinnings to make it actually work (e.g. version control).
I ~empathize with people who wish it were simpler, and agree there are too many sharp corners. (For example, the traditional CLI certainly left a lot of room for improvement.)
I can vaguely imagine the prospect that something new gets this more-right than Nix, but on some level I also suspect most ~complainers aren't appreciating the scale of the domain complexity Nix closes over in order to forge The Nix Way and square decades of contrary software development/packaging/deployment practices with it.
I generally think the UI first approach is a better way of building tools, but there are special cases where it doesn’t work due to their being so many edge cases that you need pure underpinnings to make it actually work (e.g. version control).