I just played the free trial of UO. It's probably an amazing game, and there are things that I like about it, but honestly, I couldn't get past the controls to find out. I think the controls were very unintuitive and awkward, for the most part. And the lack of a tutorial to get you past the (comparatively) steep learning curve is likely to drive prospective subscribers away. A game like UO could easily work with a modified Diablo II - like control system I think. The point and click to move, attack, and interact could work very well for it. Some of the older players might not want to adapt to a new control system though, so it might be better to add it in as an optional alternative -- and point it out as an alternative in the tutorial that needs to be added. The in-game help menu  helps a little, but not much. I wouldn't think a tutorial would be a difficult thing to add. There were a lot of things I couldn't figure out (as someone with ~ ten years of experience with 10+ MMOs, including beta testing). I did read the manual a little bit (but I had trouble finding even that), and was still pretty overwhelmed. I'm not saying that the game needs to be dumbed down, but better controls and a tutorial would make a huge difference I think.

Oh, and I was using the classic client.