You're assuming that people want to switch but I'm talking about the incentives for end consumers to switch. There has to be some strong motivation for switching, and it's not only going to be GUI design. Something about a new OS must be really desirable, either the hardware it's running on or better applications.
I'm using Linux as my daily workhorse since 2008 so I'm not opposed to it in any way. But the fact is that due to lack of integration with the OS, every Linux application is slightly less good than its commercial MacOS and Windows counterpart. GIMP is slightly awkward to use in comparison to Photoshop, LibreOffice can replace Word but definitely isn't better, pro audio applications are virtually non-existent for Linux and work only as good if you don't need any pro plugins (very few of which are produced for Linux), Dia, Inkscape, and other vector drawing programs are far less good than e.g. Affinity Publisher, and so on and so forth. Linux doesn't even have good content indexing comparable to Spotlight. Applications don't even have consistent user interfaces.
>You're assuming that people want to switch
No, I am not. That is the stance of the EU. Switching is a matter of European security.
What "people" want is already irrelevant and whether the GUI is consistent or not couldn't matter less.
I would claim that many people would be fine using something else because they use 30% of the features of the respective applications.
They end up using Windows (or Android, or iOS) also because because that is the only option when you go in a shop to buy the hardware. I have a hard time buying a computer without Windows installed even if I actively want to!