I made this point below, but Windows 10 still doesn't have the display-real-estate efficiency of Windows 7. Windows 10 wastes all kind of screen space on large, flat surfaces that a non-touch-screen user will never use. Windows 7 wasn't as pretty as Windows 10, but it was better at displaying information.
So actually, you are harmed by this decision every day you use a Windows 10/11 laptop. You live with this every day. You just don't know what you're missing.
Let's try to imagine a situation when Win10+ UI has "the same display-real-estate efficiency of Windows 7".
Would it change anyhthing? No. Because developers of the programs what are not part of Windows aren't keen on keeping "the same efficiency". Audacity 4, Thunderbird are good examples of a bad interface - and they did it disregarding the OS UI.
I've been using Thunderbird since I don't even remember when and I never noticed that it's got a bad interface, unless when they broke manually sorting folders and fixed it years later. It's got the UI that a mail client has to have. GMail does have a bad UI. Sometimes I don't understand where a message ends and where a message starts. Luckily I don't have to use it.