While FF6 is somewhat cartoony with its sprites, I think that’s less of an artistic choice but the result of the limitations of the SNES. The portraits and artwork for it are much more realistic. But it makes sense that players would get this impression of a cartoony style, the end result in the game is what it is.
Like with Wind Waker, FF9’s reception at the time was overly critical of it, and today we criticize that reaction for being shallow, but one thing to keep in mind is that back then realistic-looking games were just starting to become a possibility, and people wanted to see how far we could get. The frustration was misguided but understandable in context.
In retrospect, as much as I keep some fondness for FF8, FF9’s style was a much better fit for the limitations of the PS1. It has aged much more gracefully.