Most of the things I would add would be for convenience sake.
- Trading Post: This still needs a lot of work. Previewing was long overdue, but so are more filters and an overall better search function. Plus, there are a lot of other irritants such as not being able to click on anything under "My Transactions" without having to completely refresh the list afterwards.
- Crafting Materials: This is one of the biggest reasons people aren't out and about in the world from my perspective. I'd be curious to see what would happen if they added a chance for materials to upgrade to your level in the same way armor/weapon drops do.
- Karma: This really needs to be made account bound.
- Dyes: While we're at it, I'm still going to argue at the very least rare dyes should be account bound or the drop rates need to be increased. Spending 10-20g per character for basic colors like black and white is ridiculous.
- Skins: I'd really like to see a PvE skins locker. I find the current system terrible, especially with their seeming penchant for limited/one-time-only skins. It means you can never salvage anything you transmute and I assume if you mix up a transmute you're SOL forever.
- Guild Bank: For the love of god, why do I have to completely remove a stack from the guild bank to combine it with something in my inventory? This is one of the dumbest things ever.
- Pact Portal: Okay, so, letting anyone use any order portal was great, but I'd still like there to be some sort of ability to port to your order base.
- Map Completion: I want WvW separate from PvE map completion.
- Minis: I currently have 0 use of minis in part due to how it's designed. It's really a throwback to vanilla WoW having to remove the mini from the bank and having it take up an inventory spot. I'd like to see some sort of way to summon them through the interface like WoW has. (Plus, if I wanted to use the same pet on different alts that's such a hassle.)
- Gathering Tools/Salvaging Kits: STACKABLE, for the love of all that is holy! >_<
- Character Creation/Modification: I'd either like to see the "exclusive" options available for preview in character creation or the lighting in the makeover kits changed. Using Asura as an example, their grey skin colors look brown to me using the Total Makeover Kit, which has made trying to design one around the new hair colors difficult.
That's all I can think of for now. :P