I think Earthbound's look is very appropriate for the overall vibe the game has going for it when you actually play. It's a pretty silly game, and has silly graphics to match.

Like Secret of Evermore, much of FFVI takes place in a crapsack world. So that accounts for why some areas of the game look very ugly. It's intentional.

There are a few areas that are more vibrant and lively, but halfway through the game, everything gets royally screwed up and the World of Balance becomes the World of Ruin.