In Guild Wars 2 it's called item transmutation. Basically you make one item look like another, for aesthetic purposes.
With all these set items and such out there it would be nice if we could transmute a different appearance onto them. Crown of the Lich would be a nice looking helmet to have, for instance. That's the one that looks like King Laloriaran Dynar's. There's a lot of low-ish level armor appearances as well that would be nice at high level.
As for incentive for ZOS putting in the work, I'm sure they could be in the form of some kind of transmutation stone or some such available in the crown store.