The arguments against moving the base directories' scheme towards "merged `/usr`" are as follows:
* there's no gain in disrupting something that is not inherently broken;
* `/{bin,sbin,lib*}/` → `/usr/{bin,sbin,lib*}/` symlinks create confusing views of the system (`/bin/cat` and `/usr/bin/cat` are the same file), and dpkg doesn't support this situation cleanly: [#134758](https://bugs.debian.org/134758).
* it is possible for distributions to converge towards having all system files in `/usr` in finite time instead of shortcutting this migration with `/{bin,sbin,lib*}/` → `/usr/{bin,sbin,lib*}/` symlinks.
The arguments against moving the base directories' scheme towards "merged `/usr`" are as follows:
* there's no gain in disrupting something that is not inherently broken;
* `/{bin,sbin,lib*}/` → `/usr/{bin,sbin,lib*}/` symlinks create confusing views of the system (`/bin/cat` and `/usr/bin/cat` are the same file), and dpkg doesn't support this situation cleanly: [#134758](https://bugs.debian.org/134758).
* it is possible for distributions to converge towards having all system files in `/usr` in finite time instead of shortcutting this migration with `/{bin,sbin,lib*}/` → `/usr/{bin,sbin,lib*}/` symlinks.