Unfortunately, they won't give you a new UI. This would mean rebuilding the game engine themselves. The UI is inside the game engine, it's not server side. If they tried to overhaul the game engine, they would then have a custom version that will conflict with the regular one. They'd then have to distribute their custom version and say, "YOU MUST USE THIS ONE, NONE OTHER", as running both would be a huge problem. Anytime they changed it, they'd then have to patch it for players, just like Blizzard did. Assuming they did mess with the engine, it would also wreck every already working mod for 1.12. Given how much time and effort they already have to put in just scripting a server for you to connect too, it's unlikely they'll do this too. I've never seen a private server mess with the game engine. It just isn't worth the trouble when they can let you go get any default client then just mod it yourself.
My suggestion is to just DL the big Addon package from Feenix and start building your own UI. You can connect to any Classic server to do this. You don't have to wait for Nostalrius to open or use Feenix. The GOOD news is that once you have your UI built; it's done forever. Unlike back in retail where patches would come out regularly that wrecked your stuff; that'll never happen again. 1.12 for the game engine is the end of the road now, so having your UI the way you want it for Classic means it'll stay that way and never need to be updated or fixed again. You see, I played Classic back then(almost the entire time period), and every few weeks, they would release a patch that broke everything. So you had to keep updating or replacing mods regularly. This was the biggest problem. That problem is gone now, as anything that works for 1.12 will "always" work.
This is the Feenix Addon package. It contains most Addons for Classic. Some are borked, others are missing, but it will contain most things you need or may be looking for. You can build a whole UI using this directory alone. This is easy to find in search results as it's been linked on many sites.
http://www.ownedcore.com/forums/world-o ... ddons.htmlSo far I've noticed that Questlevels, QuickLoot, and SuperInspect don't work right. You can use AceLoot and GoodInspect, also in the directory, to replace 2 of them. I haven't yet replaced Questlevels with a working alternative, but I've only done limited work on my own UI.