I’m not saying I prefer a totally dark shell, just that if someone decides to go dark, by the same token he/she wants a dark shell, since every “easily differentiated elements” consideration applies to both apps and the shell.
And the stub point is that choice is a matter of just adding a five lines or so file starting with $variant=“dark”, isn’t it? This is not diverging too much from upstream (which defaults to a dark theme that, in terms of consistency, although not necessarily of usability, plays better with alternating gtk light and dark themes). So why not doing that in Ubuntu as a super simple temporary measure? That way I can go to Tweaks and set Yaru-dark for both apps and shell, as I did many times before with other themes. If they eventually add a toggle, then you can as easily revert the change by just removing the stub. Don’t you think? I get the “dark theme is not quite ready yet” point, though.