I don't personally see a point in implementing this in-game. The majority of the customizations are forum specific. Name changes appear in-game but need to be approved by staff. The only others that matter in-game would be custom 3D items and 3D items recolors which a) I'm assuming also need to be staff approved, and b) are uncommon enough that there wouldn't be a point in devoting resources to it. Furthermore I'm sure anyone who likes this game enough to be willing to spend money on these things is at least somewhat active on the forums and aware of the profile store.