Fire Lightning Ice aren't any more or less destructive than Floods Quakes/Volcanoes(which are fire/earth) and Tornados, actually of them Ice as an element is one of the least destructive on it's own, without the impact of wind to create a blizzard, earth to create an avalanche ... Ice actually creates very stable, if slick, homes/ground for people, fire is life giving in every corner of the world and every culture, lightning is what's making this whole conversation possible by being in a controlled form. Most poisons are derived from a liquid base.
I suspect a big reason they went with the current system was their need to have every ability from the current class/job on a persons action bars. Working with that limitation this way is perfectly fine AS LONG as they develop the content around it.
They haven't got nearly every ability and skill from the old/orig system. When they decided imposing a limit of 15 abilities to each class I have to believe it was to speed and simplify development for a version of the game that they knew was going away.
I really do hope that they don't keep this system, both on the 15 abilities front, and the way mages are now, whm isn't a whm from the majority of the old ff lore, blm isn't a blm from the majority of the old ff lore, yet the claim is, "We drew from previous FFs." What I mean by this is, to clarify, WHM hasn't every been a job that has a DD repertoire, BLM has always been the job that has elemental control to a science. This we have 2 Elemental mages not a whm and a blm, the only distinction is that blm can't heal and buff as well.