Personalised ads are beside the point. The issue is how they are personalised, namely by building a rich profile of user behaviour based on non-consensual tracking.
It isnt even clear that there's a meaningful sense of 'consent' to what modern ad companies (ie., google, facebook, amazon, increasingly microsoft, etc.) do. There is both an individual harm, but a massive collective arm, to the infrastructure of behavioural tracking that has been built by these companies.
This infrastructure should be, largely, illegal. The technology to end any form of privacy is presently deployed only for ads, but should not be deployed anywhere at all.
Will the EU fix Windows by banning the insane amount of tracking they do? Would be nice. The OS is literally at its peak in terms of being great, but all the telemetry, forced accounts and Microsoft ads keep the meme alive that Windows is awful, when in fact, if you remove those three things I mentioned, you have an insanely reliable and polished OS, all my issues with Windows have always come from customizing the core OS, it just doesn't quite behave the same, I would eventually format due to issues, the moment I stopped tampering and tinkering, I've stopped reformatting Windows.
Dark theme
HDR support
Auto HDR for many older games
Native system wide support for surround sound in headphones with hrtf
Win+Shift+S screenshot tool
It took a long time to get here, but the settings app is now better than the old Control Panel imo
If you're a gamer then HDR/surround/raytracing can potentially be huge upgrades if your hardware supports it.
Windows has had themes/color schemes since 3.0 - yes the early 90s
Ray tracing has nothing to do with Windows, either
Drawing the line between the OS and "not the OS" is really difficult. Direct X is included with the OS and DX12 is not compatible with Windows 7 so basically DirectX 12 is something you did not have in Win7 and do Have in Win10.
Dark mode being use as a short hand - pretty much all "standard" controls used to have colors and font size defined. So if an application wants to draw text - it'd use the text area background and color, likewise for buttons. Being replaced with a single boolean configuration option is just a lazy downgrade. Also I don't quite see it as an OS function - in the end it just reads the registry.
Vulcan was supported on Win7 (along w/ the raytracing) and oddly enough Win7 had a port of DX12 by Microsoft [0]. It was quite an arbitrary decision to prevent Win7 & 8 to run DX12. I suppose one of the issues is that GPU drivers (esp. AMD) do not support Win7 (or 8)
[0]: https://venturebeat.com/pc-gaming/directx-12-windows-7/
Even if dx12 is an arbitrary restriction to only work in w10 that’s beside the point. It’s a feature of win10 no matter how arbitrary.