The idea is to save you from a situation where you make a CLI config change which breaks your ability to access the box. With the "shutdown -r +10" trick, if you make the change and the change prevents you from issuing the "shutdown -c" command, the box reboots itself automatically and undoes the change you made which broke your access. It's good for remote sites without people on-hand who are allowed to work on the systems in question.
I personally prefer Juniper's CLI config system, which can commit many changes all as one atomic operation, and which can roll them back as one atomic operation. You stage a bunch of changes, issue "commit confirmed", and if you don't issue another "commit" within ten minutes, the changes applied with "commit confirmed" are rolled back. No reboot involved.