A full remake of FF6 with full 3d graphics could probably turn out quite well if they just use the original art designs from the game itself. The
Chrono Resurrection project was a good example: it looked virtually identical to the style of the original game despite being in 3d. If they remade FF6 in the same way, I wouldn't mind playing that version of it.
I didn't really see a point to making FMVs and tacking them on top of the original game like they did in Chronicles, those were too big of a contrast to the original designs. Doesn't exactly flow with the rest of the game since you go from complex 3d models with full animation to SNES sprites. If anything I think they should've just ported the game with better quality graphical assets (higher resolution sprites, etc.) and not bothered with adding or changing the art.
FF7 could use a remake too, but there isn't as much reason for that since most of the graphical presentation is still passable today. All they'd really need to do is port the game with upgraded character models (read: textures and non-deformed) and it would look fine. The backgrounds and cutscenes wouldn't really need any work, except to reflect the newer character models. Although the music could definitely use an overhaul as well.
Jam it back in, in the dark.