From a technical standpoint it sounds like they do not want to use a system that other games use where they just tint the base armor. The problem with this system is the color washes over the entire armor model so if you have armor that is base white with gold trim and you dye it blue then the white in the armor becomes blue and the gold trim becomes this dark blue color.
Currently FF14 doesn't use such a system. Armor color variations are handled by actual texture swaps which was likely chosen so they could have some color variations without armor details and trims looking terrible due to color tinting.
The development updates seem to point to resource concerns adding new colors so it sounds like they aren't looking to move away from the texture swap system in favor of a tint system as a tint system wouldn't require much in the way of resources to add more colors. So my expectation would be that we're probably going to still see limitation in armor dyes as they seem to want to control how dyed armor looks which is fine with me. Honestly the games with tint systems just end up looking terrible with many people just looking like tinted blobs of bright pinks, yellows and greens. While not being able to provide as many options, the texture system at least allows the developers to design properly recolored armor.
Edit: Just read about the update a while back where they are talking about editing the material only. This could work with similar results as the current texture swap system where only parts of a texture would be tinted, but there would still be a tint on the actual material which can still look pretty crappy depending on the 'material type' that is being tinted. An example would be a chain mail weave texture where they use gradients to black to simulate depth. If you tint this material, it would tint the gradient and not look as good as the base texture did. Another example is leather where you can see the stitching. The stitching would be tinted as well and not look as good. You could control this more by making it where you are unable to tint material on parts of armor that wouldn't look good.
Either way I hope they are reasonable with this. I'm fine with some customization but I think there needs to be some restriction on customization for the sake of the overall look of the game. I think it would make some sense to only allow certain colors on certain material and stick with a custom color palette that matches the design of the game.