i think we only get the assets from the updates, then the staff have to wire it all up to work properly with the scripts. that's why they often give the items at events rather than wiring them up to drop. i imagine it's a lot easier to put it on a loot list than it is to sort out the gumps and put in all the crafting requirements, etc.
but it's not like we're paying them to do it, and they will have priorities of what to wire up first, i doubt this is high on the list
see if it was a bigger job, they'd probably do it sooner, but cos it's in depth enough to have to get into the code properly, and only for 1 craftable deco, they might not think it worth the effort when there's more important things they have to fix or put in. that's why i say maybe when they added the peerless maps and stuff, cos they'll be messing with the cartography code there anyway