Me for one, in Warlords of Dreanor - Tanaan jungle - The Fel forge area we have a ton of cool fel reaver parts, right / left arm and leg, torso and head pieces, some half constructed fel units surounded by platforms, and it just looks cool as hek.
So being able to piece together my own fel mech would be kinda sweet!
Having Quel’dorei pieces rather than Sin’dorei.
We got some architecture in that and it could easily be achieved if Blizzard wanted. An almost 0 resource investment.
I need this for my night time room, making a fel reaver construction yard 
For now I would love more trees, bushes and plants so I can make my gardens looks more varied and natural. There are so many beautiful trees and plants in the gameworld that I would love to use on my plots.
I’d like to have a compound outside for my mounts - with actual mounts on show in it!
(Like the garrison stables basically).
Having the outdoor limit removed as the current one just isn’t enough. You are stuck between decorating your house and having an empty garden or a lush garden and a stock house.
a Rainbow effect!
Blizz already said they’re working on some sort of stable or something similar to the new pets housing system where you’ll be able to have mounts on the outside of your house 
I’d like to have the Sin’dorei items that were datamined and still haven’t shown up like the Silvermoon fencing and Silvermoon Front Door
I’d like more small, general items like skulls, axes, knives and vials. And i wish i could make a huge treasure pile, like those we saw in Dragonflight.