What's the FF6 "optional dungeon" you're talking about in that playthrough? I like Strago as a character, or at least his special ability (in case you want to cast water spells or something) but Relm was pretty worthless IMO. Lots of people loved Gogo, I didn't. Gau?...well, it was fun collecting some of the better Rages, but I don't think my game would ever even let me correct them all. The enemies just never appear on the Veldt! I had a friend whose favorite character was Umaro. Shouldn't have been friends with that guy.
My OCD probably caused me to behave similarly to your friend, micromanaging the Magicite.
One questionable thing about FF6 is that I rarely used the Espers, whereas Call Magic in other FF games seemed totally essential. FF6 is admittedly not always a very challenging game, though. It'd still be my all time favorite RPG, but for somewhat sentimental reasons.
FF5?....well, it was pretty fun when I played through it the one time on ZSNES emulator...translated by some online people, of course, MAN do I get memories of that late 90s emulation scene! But I digress....nothing in FF6 is as hard as Shinryuu or Omega Weapon, two optional super-hard bosses that appear in that "Cleft of Dimension" thing. FF4, even the "easy type" that we got on the SNES in America as FF2, is probably also harder than FF6.
I called the Nintendo "game counselor" line that you saw in Nintendo Power back in the early 90s and asked why we weren't getting FF5, this would have been back around 1994 or so when I was an FF6 addict, they gave the same answer you did: the graphics were considered a step back. Later I found out that FF4 easytype, as FF2 on the SNES, hadn't actually sold worth a crap, so that was a problem too, probably a bigger one. No, FF4 and FF5 don't have very good graphics. Of course, Square hated Nintendo's thumb being up their butt all the time, hence what happened in 1996 when FF7 went to Sony, thus confirming that 90s Nintendo had a perennial, maddening inability to do what people actually thought was cool.