Correct me if I am wrong, and I may be, but isn't a large portion of the UI server side? I was under the impression (possibly mistaken) that this was done to increase security v. unauthorized mods and botting tools. If that is in fact the case (and if it is, I do happen to agree with it) and mods would have to be server side as well and require a public API to even make. I'm not sure that I can see SE doing that. I know Yoshi-P has mentioned mods in the past, but it is a very tricky slope for SE to walk down. I'm sure the first concern they have is how to ensure that the mods being used are secure, safe, bot free, and don't provide an unfair advantage to some players. Re-arranging the UI is fine as far as I'm concerned, but I for one don't want see what I see in WoW - You can't join our guild unless you have Mod X.