Transmogrification is one of those features which supplies endless variety and no actual benefit to killing monsters. As such it is a very interesting game feature to watch going forward to see if any other innovations are added. At the very least it removes us from suffering clown suits while we play; which is darn good.
I had an idea for TransMog v2.0 which would allow an illusion set to be set in the same way a title is selected. This is a specially prepared illusion which displays one set regardless of what you are actually wearing. The character would prepare the gear in the same manner as transmog, and then an illusion of that set appears “always on”.
Thus a leveler or raider who replaces gear often will always look as intended. The cost might be high, perhaps even applied by carrying a specific item which sits in backpack in the same way a haunted memento gives you a shade which follows you. If it was really meant to be for the high rollers, and a profession push was needed it could be a craftable item which needed a synergy of several conflicting professions to craft.
Just a thought.