I agree that there should be elemental reform. There also needs to be some changes to lore also, and it's best to do it sooner than later, better pre-2.0 than post, but that's another issue.

On to Fire/Lightning/Ice for thm/blm issue. I think of it as Thm/blm's having the destructive magical elements. Not that Water, earth, and wind can't be destructive, hell you could beat a person to death with a dildo if you really wanted to, but Fire/Lightning/Ice just seem more destructive by nature, while the other three seem more life giving in a way.

Part of the problem is now that if you get attacked by a bunch of mobs strong to fire, you're likely better off picking them off one at a time with Lightning, or a single strong enemy stong against Lightning, surrounded by non-aggro enemies, fire is out of the question since it's exclusively aoe.

Maybe making the elemental "wheel"s only apply to specific types of monsters such as elementals and Esper types, and to have the rest of the enemies set up on a case by case basis, with thm/blm elements in mind would really help. This would also make elemental abilities that do not belong to mages less restricting.

And/or change the way magic chaining works. Use the Stone -> Stonega concept for all elements, and also a reverse.

So for instance Fire -> Fira (aoe) would make Fira a strong single target attack, but the other way around so Fira (aoe) -> Fire would make Fire a moderate aoe attack, roughly on part with Fira (aoe). Doing this with all the elements would make sense and still be limited by the possibility that the target ends up resisting the spell keeping the player from being able to chain.