So, okay, we already know that the devs are (at least for now) intending to allow UI mods with full script-interaction via LUA.
That's a powerful thing.
A rather stable factor of ESO is that while there are many skill trees, there's only a very limited set of active quickslots for skills (what was it, 5 skills and one ultimate? or something like that). That's all fine and dandy...
But what about UI mods that add more skillbars, allowing PC players to basically hotkey every single skill they have? That would be a *massive* advantage in both PvP and PvE over regular players - not just "see what you can do in a better way", but a full-on "do more stuff". Afaik making such a mod would not be difficult at all, and unless there is some hard limiter for skill-number per fight on the server, then I don't see how this could be prevented, tbh, as long as UI mods are allowed.
Or does Zenimax consider it fair, when unmodded players have (e.g.) a total of 8 active skills to choose from, and modded players have (e.g.) 36+ in the same battle?