I love all these ideas. The way I see it, like most everyone, I like the idea of changing it so that dye is applied to finish undyed cloth/straps/leathers/etc. after the fact.

I think that allowing NPCs to do pre-defined colors on finished items only is a great idea. Say, allow them to use the pre-set color pallets that are currently in the game now.

Add the ability to mix-and-match like Ami suggested. This is a brilliant idea. She said it best 5x5x7...

And what do we have?
Lots of customization to make our characters look like WE want them to.
More options for people who want nothing to do with crafters.
More options for crafters to participate in the economy.
Simpler recipes that increase the number of finished products while simultaneously reducing inventory load
Gil sinks

I look at that and see a relatively minor change (in the grand scheme of things) that provides solutions to multiple issues. IMO, its a win-win plan!