Do you like hyperlinks in the chatlogs? Links that when you click on, you get to see the graphics/stats of items. You can even link your quests in the chatlog so that others could see the quest details.

Ever bought a pair of cute red shoes & you found out that its actually pink instead of red? Even the same red could be different in shades on different materials.
With a character wardrobe, you could just click on links in the chatlog & see how you look like with the items equipped.

Personally, I feel that they are great additions to the UI which are already present in other mmos.

Bonus question, is an AH being worked on for 2.0? If I am not wrong, the AH is the 2nd most wanted feature after battle adjustments in the 1st poll.