The rumors of the Highborne's poor fashion sense seem to be true.
That Azshara was the most beautiful of night elves is practically regarded as fact. Unfortunately, her own eye for beauty seems to have been as limited as that of many of her brethren, at least judging from the garish colors of this gown. 'There has only ever been, only ever will be... one Azshara.'
The "Highborne's poor fashion sense" may be a reference to the Highborne collection, Merchant Kendra's comments, or possibly something else, like the general look of Highborne NPCs.