I mean the main thing really is you'd need an actual reason to design it too when the current design works just fine. Got a role you want but have particular needs? Scroll on through until you find one. If not, then maybe it's not your kind of role.
Having seen many KRMMO's try a talent tree system, all that ends up happening is you pick a particular meta for your kind of job or you get laughed out of existence or just will have a much worse time overall if you don't pick the "correct" path. Want to try a hand at talent trees currently? Meld materia...oh wait, we pick Crit/Det/DH when not picking the Speed you need because Tenacity and Piety are memes.
I'd rather not have an illusion of choice but given how much effort would need to be put in there to make it not your typical KRMMO system, that effort could be better spent elsewhere. It's why this suggestion really doesn't work for this kind of game.