Time to get a tuneup on your snark detector. 
I was making fun of folks who complain about having to go through the horrible effort it takes to change a preference because the default isn’t the way they’d set it. 
A tiresome, irrelevant waste of development time that could have gone into solving features that don’t work properly. Just my opinion of course. There is not enough space on a larger screen, so I can’t see how it could be useful on a small laptop screen. Luckily I don’t have to deal with it and it has gone…forever.
I turned it off as I can’t find a use for it that improves my workflow with 3 monitors.
I did create a key command for - create sampler track - when an audio region is selected this automatically brings up the sampler editor in the lower zone. Then I have to click the arrow in the top right corner to get it to open up big on one of my other screens in it’s own window which still doesn’t close it in the LZ.
I have preferences set to - double click opens editor in a window - but that doesn’t wotk for the sampler track. Am I missing something simple?
I agree with everything you have said. I think the software is worse off for it
I don’t hate it but i don’t use it. I will use it for the sampler though. Just not at that point in any of my projects.
You’d have to ask why the sampler wasn’t integrated into the vst instrument rack where it logically belongs.
The fact that you can see your notation screen under the project is great.
I should like to open the key editor in a full window by double click (default editor) whilst opening the score editor always in the Zone. I have not found a way, even using prefs.
Z
Not sure if that’s possible, since the Lower Zone always seems to open the Default MIDI editor that was set in Preferences | Editors on double click.
However you could assign a KC to Open Score Editor in Lower Zone.