Have you ever seriously tried to max your character's stats?
I'm not talking about raising to maximum levels (99 or 100 usually). I'm referring to raising the character's stats through some approved or illicit method.
Some of the ways I recall are:
FFVI: Equipping Espers for level-up bonuses.
FFVII: Morphing or winning items that boost a stat by +1.
FFVIII: Devour, equipping a GF with a stat level-up bonus (like Jumbo Cactaur), and refining items that add +1 to a stat.
FFX: Maxing out the Sphere Grid.
FFT: Level Up/Level down in different jobs using Degenerator traps.
I certainly tried with FFVI but once the characters reached 99, there was nothing left to do, short of using a hack. I also did some halfhearted attempts in both FFVII and FFVIII. But I eventually gave up because I realized that there was no opponent so challenging that maxing stats was really necessary.
Bottom line, it wasn't cost-effective for me.