I think the requests of users have changed. Today People want more Out of the box stuff. I will try to resume my thought:
Integration.
Users are looking for integrated UI and this is the reason of the success of Tukui, nUI and Compilations. Using a base UI, users can add a raid frames, a damage meter, any other addons etc. But Today, People prefered to reduce the number of addons.
Adaptation.
The possibility to switch all the user interface depend of if you are a healer, a tanker or because you change your spec. I know some people have two or three installation of WoW, with differents addons, different configurations.
Customization and Simplicity.
More the list of customization option are big, more you loose in simplicity. These two words are opposite in fact. For example, you can do what you wish with oUF, but you have to learn LUA. Some authors prefer to limit the customization and their addon is easier to use. The goal is to find the right middle between customization and simplicity.
I am not agree with Xinhuan when he say the golden age of addons is over and there is no more innovative stuff. This is more because you are staying in the world of Ace. Ace did never evolute and is still in version 3.
I want to highlight RDX 8, the addon I am responsible. RDX 8 is about to be the new golden age. Just spend 15 minutes to test it and you will be like all these people who PM me or send me a email, explaining their surprise and congratulating the job done. You will understand the concept.
To install:
RDX core and mediapack:
http://www.wowinterface.com/download...7-OpenRDX.html
http://www.wowinterface.com/download...MediaPack.html
RDX Theme: (Download and install them all)
http://www.wowinterface.com/download...3-OlokAUI.html
http://www.wowinterface.com/download...XenoraAUI.html
A quick tutorial has been integrated at startup of RDX.
For any questions, you can use our RDX section here on WoWI.
The final version is coming soon with so many more theme.
Cheers