Originally Posted by
goblingirl
For sentimental reasons, sure there is. I won't be deleting my Rhok, no matter what.
I haven't tested it on my beta toon yet; but there are also some on-use items (i.e. amongst tabards) that I'm unclear about. Unsure if transmogging a tabard from the appearance UI actually gives you the on-use effects, or if you actually need the tabard physically equipped.
Anyway, it's entirely reasonable to be super careful what you delete, amongst the more rare and definitely the unobtainable items.