No you're right, they DONT need a talent tree because the current Actions menu accomplishes that except that it's menu driven and not visual. They work identically except that the trees give you a visual representation. The best example I could give is this (btw I don't care if you like the license board from 12 or not. just using it as an example):
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Imagine this. Now take all the abilities/traits that are currently in our Actions menu on the board. Scatter them out appropriately throughout the board (cures for WHM, nukes for CON and debuffs for RDM). They would also need to add in things that help that class (WHM would have like +5% potency, RDM could have +5% cure casting). Not just limited to stats like that they can get really crazy (BLM: When an offensive magic spell crits your next cast will have 20% of its cost reduced)
Now you further divide each section (impose limits to prevent abuse) into levels. Keep it simple for now with 5 levels. You need to put a certain amount of points into BLM Lv1 before you can use points on abilities/skills/traits in BLM Lv2. This would prevent overreaching that is happening now with people using Rank 30+ traits on different classes.
So you get what I'm saying? They don't need the tree or the talent points. Thats just a visual representation of what they currently have in place in the Action Menu.