I don't think the entire battle system was broken, there were just some spells and abilities that were disproportionally powerful. These just would need to be nerfed to make it more "balanced." Limit their usage, lower a character's MP or ability to regain it, and lower the damage. Or you could just increase the levels/stats of all the baddies. It's really not all that complicated when you get down to it.
Then again, I didn't overly mind the ease of the game. I play most JRPGs looking for great characters, an engaging story, and at least some entertaining gameplay (which is often fulfilled by exploration and sidequests). There are some notable exceptions (FFT), but some of my other favorite RPGs aren't much more difficult than FFVI. On some of my second+ playthroughs in other RPGs years ago, I sometimes utilized glitches or outright Gameshark just so I could enjoy the story without feeling the need to grind.
EDIT:
I approve that your answer for how to improve FF games is "be more like FFT."Originally Posted by Deli