Let's assume that the reason all this armors are undyeable is because they are iconic.
Let's consider the following questions: Why can't we go against the icon? Does it harm the icon itself in any shape or form? Do White Mages stop being White Mages for not wearing white? Does a Paladin stop being a Paladin if he doesn't wear blue (or whatever color scheme they use)? Wouldn't it be like saying that the habit makes the monk?
And, finally, if going against the icon does indeed harm the icon... is it a bad thing? Why?
Personally, I think this whole 'they are icons and as such they should not be dyeable' seems like a personal aesthetic choice forced into everyone else. Having these items be dyeable doesn't affect your aesthetic choice at all (because, arguably, their original dye color would be the iconic one), but not having them does affect other people's aesthetic choice.
Let's consider the following questions: Why can't we go against the icon? Does it harm the icon itself in any shape or form? Do White Mages stop being White Mages for not wearing white? Does a Paladin stop being a Paladin if he doesn't wear blue (or whatever color scheme they use)? Wouldn't it be like saying that the habit makes the monk?
And, finally, if going against the icon does indeed harm the icon... is it a bad thing? Why?
Personally, I think this whole 'they are icons and as such they should not be dyeable' seems like a personal aesthetic choice forced into everyone else. Having these items be dyeable doesn't affect your aesthetic choice at all (because, arguably, their original dye color would be the iconic one), but not having them does affect other people's aesthetic choice.