Elemental Wheel, What's the point?

[Alhanelem]

It seems his issue is more that some mobs that don't really have an obvious element associated with them are strong/weak to certain elements. I would argue it's usually pretty obvious what element would be associated with a monster (e.g. birds resisting wind, fish resisting water (not that we have a water spell at the moment...), coblyns and other desert mobs resisting earth), but I understand where he's coming from in that case.

the only problem that should be fixed.. give light spells to conjurer and all elementals to thm.. and the problem is solved.
then the thm can switch through all elements, depending on the enemy's weaknesses.

The ironic part of this would be that thaumaturges used to be associated with light and dark, not the natural elements...
But your proposal doesn't address any problem. They gave the minor elements (I call them that because they're extra- most of Final Fantasy has been based around only thunder fire and ice) to conj in large part so that conjurers wouldn't be helpless and be balanced against the other classes in terms of being able to fight solo- ironically something the OP seems to expect of all classes.