I always thought that one of the big purposes of "sudo" is to prevent operator errors. For example, if I want to inspect the .deb file and accidentally type "dpkg -i" instead of "dpkg -I". Or if I am examining logs on a server, and mistype ">" and "<". Or if I typed "make install" and failed to set PREFIX to a local directory.

It also helps a lot as a voluntary "logging" solution -- if you collect syslog on your servers, this can record which commands got run and why things got worse. It is not security solution, you'll have to make a "social convention" to never do "sudo su" or invoke ! in your editor, but it helps to detect accidental mistakes.

As for secure console, you can do this today! Make sure "k" is enabled in magic sysrq flags, and then you can switch to VT1 (alt-ctrl-f1) and invoke SAK with alt-sysrq-k. This'll kill everything on the current VT, and give you a clean login prompt which you can safely log into.

Finally, even with a single user, the privilege separation can help a lot with data protection. Just set up a backup process to run as root, into local directory where only root can write to. Then at least your data won't get deleted.