[tobias12345]

By splitting / and /usr you create problems for packagers: Where do all the files need to go?

Does cryptsetup need to go into /sbin or /use/sbin? Does network code belong into / or /use?

Must users will not care, but some might need either of them to set up their file systems.

If you pace something into /, then you also need to put all libraries and binaries that needs into /. That will rapidly blue up the size of /. It is also not automatically testable, so distributions will get things wrong (as they repeatedly did before).

You could have a script to only put the stuff your system needs into /... Most distributions use such a script for their initrd, which contains everything necessary to check and mount your root file system. So you could just extract that into / and be fine with it:-)

Or just use your initrd as that rescue medium.