Long-legged Velks are mentioned in the http://www.imperial-library.info/content/interviews-skeleton-man, so presumably they are fairly common creatures on the mainland.
Among other ideas, one of the suggestions as to a commercial usage for the Velk was that after it had filled up its crop on nectar from local flowers, the Dunmer farmers would induce the beast to vomit back up the processed nectar, collecting a form of "honey" from its stomach that was highly prized by the locals.
The idea of the silky underbelly hair being used for some kind of expensive clothing is fairly good potential idea, too. We'll see when we come to writing dialogue about the creatures