I would like to propose something I feel is badly missing, especially considering the amount of cosmetic items and general customization available.
I like to call the feature "Dressing Room".
Ideally, it would be a centralized system to preview and apply cosmetic items, dyes, possibly something connected to crafting stations so you could preview weapons and armour.
As most people probably know, the preview in crown store is pretty lackluster. You can pretty much only turn your character/face around and that's it. No way to zoom in and out, you can't reposition the camera at all, and you're stuck with whatever lighting and background you have based on where you are. That's bad enough, considering you need to take a good look before you spend crowns. But it gets better:
Say you bought the big pack of hairstyles from crown store. Now it gets really annoying. The Collections->Appearance window occupies half the screen, and your character is in the centre of of it, being half covered by the UI window (you could move the camera position before, but it only move it a little and in the end solves nothing). There's absolutely no way to zoom in or out, rotate your damn head or anything while keeping the stupid window opened. The list of stuff doesn't even have any "miniature previews", so unless you have really good memory, you don't even know what are you applying. Good luck not losing your nerves after reopening the collections window for the 10th time.
Crafting? With the exception of one half-working addon, there is no way to preview armour, so you have to constantly switch between the game and a browser, and are dependant on other people's screenshots to have even the slightest idea what are you creating.
Dyes? There's no way to preview locked dyes (makes no sense - I'm not going to grind achievements for something that might not even look good when I actually apply it to something). You're stuck with the lighting conditions of the place you're at, and 99% of the time, the sun angle is so useless you can't get any decent idea anyway.
I'd like to see a system where you could do all this under configurable conditions. In a nutshell, it would be freely controllable camera, selectable background, customizable lighting direction and intensity. There needs to be builtin crafting preview with more or less the same features too.
Hence, a dressing room. A place where you could play with customizations independantly of where your character is, what time of a day it is, without having to switch between various interface windows, etc. etc.