(edit: gonna put this on hold, I have not actually looked at the the custom thingy here since the last time I needed to use it)
edit02: Okay, looks the same.
I know I have suggested this before, but I consider it well worth bringing up again.
A function where you copy your armor/weapon. Commonly people use a "doll" and you copy your old gear onto it. Then you equip the new armor/weapon you want to customize and copy from the doll onto your new things.
The customization doll is a lot smoother on all accounts, because you can work on the whole look in one place and you do not have to worry about losing the settings because you accidently click away the menu or whatever and is forced to start over from scratch.
You can add some more advanced options such as being able to enter a number and the part with the matching number will be brought up instead of you having to browse through a gidzillion parts to find it.
The symmetric function is also very nice, where you mirror left and right side on the doll.
I am a bit spoiled though, since I am used to being allowed to use the full range of custom parts. Magical auras, ghost lanterns, weird body parts, tattoos, changing the default skin and so on.
edit03: People complained about me walking around in default armors from like level ~1-9. It is because it is way too much work for me to customize my armor the way it is now. As in, you need to do it all over again when you get a new armor.
People who have played elsewhere have most likely bumped into a variation of the doll.