In light of even more Crown Store exclusive dyes being put up on the Crown Store as dye stamps, I feel it's important to bring up a point that I know other people within the community are vocal about. That is a request for the option to permanently unlock these dyes. So, instead of having the one-time use dye stamps, there would be an option for ESO+ members to dye their costumes in those colours with the peace of mind that they can freely change it again later on
and use it in combination with colours that aren't the ones locked on the dye stamp. Non-ESO+ players would also have the ability to dye using it, but obviously not with costumes, but it depends on what ZOS wants to do about the dyes if they did decide to make any changes at all.
I know ZOS are looking for ways to improve ESO+, so perhaps these Crown Store exclusive dyes can be unlocked for ESO+ players if those players are subscribing during the limited-time period that the dye is on the Crown Store for, as part of the subscription bonuses. Or, if ZOS doesn't agree on it being apart of the subscription as such, they could make it so only ESO+ members can permanently unlock a dye by purchasing it on the Crown Store, but that would be their choice to make.
Also, to better demonstrate the inability to use these colours in combination with other colours that aren't locked in on the dye stamp, here is a picture of my character wearing a costume with the emperor red dye, alongside two other dyes:

And here is two images of my character previewing two different dye stamps (both containing Crown Store exclusive dye colours):


And now this is a (poorly photoshopped) image demonstrating what is currently impossible:

I
cannot combine my emperor red dye with either of the Crown Store exclusive dyes, because the way that the dye stamps work mean that I can only dye my attire with the 3-colour combination that the dye stamp has already pre-determined. I feel this is a shame, as I am not free to experiment with the colours locked in these stamps with the other dye colours I have unlocked. Permanently unlocking the dye will prevent this, as I would then be free to combine whatever colours I like in any combination I like.
tl;dr: Requesting ZOS to give us an option to unlock the Crown Store exclusive dyes permanently, instead of being locked in a dye stamp.
EDIT: Image formatting.
Edited by KriHavok on April 13, 2017 5:46PM UESP Staffer & Wiki Editor