TERA. It's such a big deal, in fact, that changes to TERA's system brought on by the recent Reaper patch have resulted in a titanic forum protest thread that's well over 30 pages long as of this writing.
In a nutshell, TERA's dearly departed remodeling system allowed players to alter the look of individual gear pieces. It was similar to World of Warcraft's transmogrification mechanics, but it has now been replaced by a system that necessitates grinding for tickets that may be exchanged for whole armor sets.
[Thanks everyone who tipped us!]