UI is one of the most important elements in a game. It is the point of contact between the player and the created world. If for whatever reason that contact is hindered in any way, the game will suffer regardless of any other considerations. It's no surprise then, that once a suitable UI schema was found, virtually every MMO since has used this model. I don't know enough about MMO history to correctly pinpoint when the modern UI first showed up, but that's not important.
What I want to talk about is the malleability of the UI in LOTRO. It cannot be denied that WoW probably has the best malleability of any UI system out there with the plethora of community-created addons assisting with any conceivable function or goal from the auction house to raid healing. LOTRO's UI as far as I know does not support add-ons. For me, that hasn't been a problem and all the content in LOTRO has sucessfully been completed without the need of add-ons - not to say that an addon to help with healing, for example, wouldn't help. It's just that such a lack does not make content impossible. A weakness of WoW might be that their addons have become a double-edged sword in this respect. So many players use a particular add-on that content is designed with that add-on in mind. If you don't have it, the content is next-to impossible. We can't blame Blizzard for this either - they don't want their content trivialized so they
have to react to the add-on, or ban the add-on. This latter approach is a slippery slope after the precedent of allowing add-ons for so long. I don't see them going this route.
LOTRO, on the other hand, has no add-ons, like I said. They don't have to deal with this particular problem, but it still holds true that a UI with any problem what-so-ever will affect the perception of the game. The UI is like the window through which we view and interact with the world. A dirty, scratched, or even broken window will cause problems in that regard. LOTRO thus offers some malleability to their UI in the form of scaling and moving the elements around. In some cases, certain elements can be turned on or off.
Myself, I stick with a fairly
basic UI set up - not different from the default. Where I do change quite a bit of the UI is the hotbars, and I think that holds true for a lot of people. We grow used to a certain pattern of movement when it comes to our hotbars therefore there's probably quite a few different set-ups out there. I have used a few different ones myself before finally setting on the one
I currently use.
Because your hotbar layout is so personal both to you and and your class, getting into a discussion about why I put them where I do wouldn't benefit many people except to say that my goal was to minimize mouse movement as much as possible while retaining logical groupings of skills on those bars. So, all my bars are located in one spot and the placement of skills and items I put on those bars is well thought out.
Would a more customizable UI be better for LOTRO? I've already mentioned that there is no content in the game that cannot be experienced successfully with the current UI, but is there still a trouble-spot that hinders gameplay? Some argue the scaleability of the UI is one such place. As you scale your UI up or down, the art assets are squeezed to fit the new "contours" so to speak. As this art wasn't designed for anything but the default UI size, illegibility goes up as the UI is scaled. As such I keep my UI scaled to default. Honestly, I don't need things any smaller because my screen resolution gives me nice large spaces to work with. Others might not be so fortuante and a smaller UI would help with that. To remedy this situations, all the art would have to be recreated in such a fashion as to work with scalability more closely, which would be a big project. Some argue it would be worth it, and my earlier statement about the supreme importance of the UI would suggest so as well, but considering the number of people function well in the game with the default scale, resources devoted to such a probject might indeed
not be worth it. Only those with the data can know for sure, and those are the developers. We haven't seen a focus on this issue so I imagine we won't in the near future.
Generally, I think the UI is satisfactory. It's not perfect, but it's close. No human creation is, but that's a philosophical discussion that doesn't belong here. We're looking at a simple UI that has been duplicated over many different games for a very good reason - it's a good UI. It wouldn't be used if it weren't. LOTRO offers some customizability but not so much as to become overwhelming or problematic in other areas (like I mentioned with WoW). The UI "window" is mostly clear, unscratched, and unbroken.