Provided that the presets are defined in the game somehow, there is no reason that they would be any less accurate than remapped graphics.
Personally, I have no need for them as I like messing with the colour sliders and dont really care about the (as I see them) quite unattractive default colours. However, it does seem to be a popular request.
Here's a thought: could such colour presets be defined in the playerclass (I don't think that has been suggested, but I may have missed it)? The format could be the same as normal DECORATE translations but perhaps with the addition of giving the preset a name. Zdoom would have the ability to read presets from the player class. The player setup could have a selection field a bit like the skin and voice options choices but for colour. The sliders could still also be used (with the selection field reading "custom") instead. This suggestion would also allow the use of custom player classes that use different graphics and allow them to have suitable pre-defined colour selection options.
