It's not complex as much as it is rather redundant to have multiple resources (three if you count spells cast from HP) for magic in the same way that is also rather redundant to make many DoW skills that use up MP.
It's not complex to use TP and MP, it just makes you wonder why even bother doing that.
And mages have to manage their MP pool, position themselfs out of harm's way while still being able to quickly aid a party member or attack the mob, watch buff / debuff timers, backup healing, etc, etc.
The devs could also make elemental affinities more useful and mages have to consider elements. Make more spells only work on special conditions (like gravity - or was is that other bind spell whose name I forgot? - only working on mobs that are moving when hit). Have some spells also change effectiveness when attacking from certain positions.
There is room to increase micromanagement, complexity and allow higher battle dynamics without plain and simply adding TP cost to spells. It's like some RTS game adding an extra resource just for the sake of having an extra resource instead of adding more unit formations or unique unit abilities.
See the rest of my post for answers. And once again I have to remind you that TP is already darn useful for cross class skills the way it currently is.
