Well not really necessary since you only need 1 thievery character, no point in having multiple. Also bartering is way better eventually since you can't steal forever from the same people. I prefer bartering first, then using up your thievery when you see really good items, then back to bartering after you can't steal anymore.
Stealing for gold or skillbooks is better because you can use gold on anything, and you might not have a lot of good items to steal, and good items are temporary anyway.
