Tablets like the Surface and the Dell Venue only sell when they're on price cuts for the most part. And they're going to keep doing these promotions until they can't find any consumers to fall for it anymore.
I dunno about the Venue, but the Surface Pro line has been selling modestly well since it's introduction, and the Pro 2 has only continued that trend. It's the RT, which MS expected to fly off store shelves, that's been the huge disappointment.