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.
But even if I accept your premise, I’ll remind you that Windows 7 came out 19 years ago. I didn’t exactly own a 27” 4K monitor in 2009, and a 14” or 16” screen laptop in 2009 would not have been thin and light like it is today. 2009 was like “my bezels are over a half inch wide” era.
The OS is fully scalable as well. You can just make it smaller in a very granular way. Windows 7 wasn’t capable of that.
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.