The class system may be a relic, but it’s a relic that the story and gameplay is based on and you want to erode the base of the game away just for something shiny that has a couple hours of story quests at best and a job with just 20 levels?
It’s unfortunate the way the old class system works and I don’t disagree that it is constricting and robs us of classics like nature magic and the thief job, but the game is stuck with it unless they do a complete overhaul since the stories and mechanics of the ARR jobs depend on it.
But geomancer would make no sense from a story perspective since part of the plot of its existing story only happens because of the fact that it has no job stone and a whole aspect of its power (stars) isn’t even rediscovered until the Stormblood AST quests, so those at least would need a complete rewrite. It is introduced to us as being a far-eastern form of 2 existing magical arts to the point where its magic is fully compatible with AST and they can pull from the same source of aether and do much of the same things.
I don’t understand your point with the other job comparisons either. There’s only so many weapons in the world which is reflected in the fact that they’re kinda scraping at the bottom of the barrel for melee/ranged physical job weapon ideas and needing to get more creative, but at least those jobs you mentioned use them in completely different ways. Magic is the power of the imagination made into reality and can be absolutely anything at all but you just want us to have a job that reuses the exact same spells that CNJ already has.
They’ve already said that we can expect more unique jobs that aren’t connected to the existing list of past FF jobs so they’re definitely not tied to it and I don’t see the need to rewrite existing job quests or chop away at the base of the game in order to plunder CNJ’s spell list. That is way more effort on the dev’s part than I’m sure they’re willing to spend on just 1 job out of what will soon be 22.