Well it's certainly possible but it would mean adding more warehouse slots which is not possible at the moment. I found out the hard way when I increased the amount of inventory and warehouse slots a couple of updates back that Iris is a bit fragile if you add too many and I ended up having to reduce them again a few days after.

Why would you want this anyway? Just for easier item sharing between characters or you were perhaps thinking about non-tradable items being shared with your other characters as well?

those non-tradable items..love to share them with my other toon but cant trade it

Not really going to happen. If I were to add an account warehouse I would add another limit to items that would allow some items to be placed in there but most untradable items would remain untradable.

Agree... but it would be good to send items that are tradeable way more easier. Example, when i send items to craft , and i need send mats to my cheff and card master. placing them on a server warehouse can reduce my time spent sending 3 per 3 items/packs xD