* Graham P Davis
My own reasons for using 'root':
(1) The last time I had to use it was a few weeks ago when I'd installed something from a factory repo and my user KDE session was scrambled. I could login OK but various applications were not visible on the desktops - including YaST - although the task icons were visible on the task-bar. I logged into 'root' and uninstalled the offending software and all was OK.
(2) On another recent occasion, I needed to remove (by renaming) the .kde4 folder but a new one was created before logoff which contained the same problems I wanted to fix. I therefore logged on as 'root' and renamed the folder from there before logging back on as the user and so getting a clean .kde4.
(3) This last one also happened recently and is an oldie and a weirdie that I thought had gone away. On a new installation, I found that the sound wasn't working too well. I checked and changed the volumes in YaST but this didn't work as it should so I resorted to logging in as 'root' and changing the volumes there. This time it worked.
And *all* of the above could be solved much easier/quicker/simpler by
logging into a text console,