Well, The first thing I'd love to see, even if just as a "developer tool" is the ability to create an "offline server."
Basically, it's the base URU client, running locally, that allows for the testing of objects and tweaks in the Alpha stage (I.E. to see if a tweak improves or breaks the game), without running the risk of crashing an online server for multiple users.
Like some, I would love to see a more modular approach to the KI interface (Custom fonts and themes, anyone?), as well as support for an MP3 canten, like so many others have requested.
I think part of the reason why the MP3 canten was dropped from the MOULa, was because the average MP3 is about 1-3 megabytes, for about three to four minutes (approx. 1 MB for one minute). The average High-speed internet connection during Uru's close on Gametap was between 512 kilobytes and 1 Megabit.
Now, a Megabit does NOT equal a MegaBYTE, but I'm sure that's common knowledge. A bit is one-eighth of a byte.
So, using the aforementioned numbers, the average speed of a "high speed" connection, in standard Byte notation, is between 64 kilobytes and 128 kilobytes per second.
Not impressive, huh? That means that it takes eight seconds to load one minute for an MP3. But, since most systems don't play the MP3 until it's FULLY downloaded, your sound could lag out by up to half a minute over your friend's.
I think the solution would be to implement a steaming platform into Uru, which would allow people to stream such music easily and without lag.
Of course, We'll have to wait until we can see how exactly the client handles changes in an Age, such as if a server has a different texture pack than the one on the client.
But, that gives me a suggestion to implement, either in the canten, Imager, or KI: I'd love to see if someone could, later down the road, integrate a media player into the device.
I mean, how hard could it be to make a plugin that allows a media player like VLC to function on a KI? (VLKI, anyone?)
But, perhaps that should be included in my suggestion to make the KI itself more modular.
I mean, think of how much potential the KI could have. If you were to find ways to integrate other programs inside it, such as an e-mail client or even a web browser (I've seen a few games take this approach.), all of which you could access without having to alt+tab or close URU.
But, meh, I'm just a dreamer.

I should probably learn to code, if only to understand how difficult it would be to implement these ideas.