Remove all the weapon/armor skins from the in-game and add them to the gem store. Let only the stats be found in the game from basic to legendary/ascended but the weapon/armor will have the basic look
Gem store items being purchasable with in-game money will be considered as a grind for those who want to do this and not spend real cash.
In this way the Style tab in Gem Sore will be a vast “wardrobe” from which each player can choose his own look.
Add different prices or requirements for skins like " required lvl 65+ armor to apply this skin" or “required an exotic weapon to apply this skin”.
Of course people can buy the required item and use the skin on it and then he can use a transmutation stone to get it to a different level weapon/armor.