Nah, FFVI has chamber pots AND toilets. Kefka even has a rant while pacing about in a prisoner's cell, which, of course, comes complete with a toilet. I mean, he strikes a pose on top of it.

They're there. In some games. But in the older ones, when pixels are so limited, why include them when they just eat up precious space/memory? XD

Current ones don't have that excuse, though.