I can handle a locked UI in the sense that the minimap is the same for all players, the actionsbars are the same, you can't move or make anything smaller, etc. That's all well and good -- I'd like to change it, but it doesn't alter my gameplay experience in any way.
But there are a couple things that are unacceptable:
- Operations Frame. In the middle of a fight, I don't need to see who has my Mark of Power buff. Speaking as a healer, the current health -- and possibly debuffs -- are the only things I need the Operations Frame to show. I can buff everyone before the fight and be confident buffs are still up. Moreover, even if you're going to show buffs, they should not be be emphasized more than the person's health, which they are by being larger than the health bar.
- Target of target. Not showing target of target is patently unacceptable. A Sith Inquisitor has a 60s CC that is broken on damage; if 1 damage class hits it with something while trying to figure out what the tank is tanking, that CC is broken and can't be used again for another minute. In organized grouping, this isn't an issue, we'll learn to wait -- but in PuGs (which you heavily emphasize in the leveling experience) that isn't possible.
- HoTs+DoTs. Currently, I'm completely unable to tell when my buffs/debuffs wear off from my target when there are other classes using the same abilities on my target. Affliction is an example of this for a Sith Inquisitor. There's no emphasis of MY affliction from anyone elses. If we have a 16 man Operation, it's going to be impossible to know when to recast affliction unless we all just get in the habit of using it every 15seconds. In this case, what's the point of showing debuffs if we're just counting in our heads because the debuff bar is that bad? This just isn't acceptable.
- Macros (mouseover) or better targeting needs to be implemented. Without clickable nameplates ala WoW, in a Warzone, I'm unable to quickly switch between targets taking damage without focusing on those terrible Operation Frames. JediKnight over there just got to 40% and needs a quick heal: now begins the process of either trying to actually click him or find his name among ~a dozen people and hoping the heal gets off in time to save him. Relying on Operations Frames is a bad design for PVP healing, although permitting mouseover healing would be a stop gap from entirely changing your targeting system altogether.
If you don't want to take the approach WoW took and permit addons to literally hold your hand through the entire thing -- which I would applaud -- you need to fix these errors and/or limit what addons are capable of doing. The problems I've pointed out are just ones I've had while leveling, and it's only going to get worse from here. I doubt you have the time to seriously devote to a UI overhaul to appease everyone, but that's the value in having an unlocked UI and enabling mod support. The community: we are going to be able to design and maintain a much better UI support system than you are capable of -- hamstringing us is only hurting this game.