Great thread… I feel like I should chime in, being as this is the industry I am involved in but you guys seem to have it all covered.
I recently did some designs for 2 different manufacturers of Appliances and flat screen TV’s… in both instances I was told not to make them too fancy because they were for Costco and they have an ethos that if the display is too slick their customers will feel they are not getting the best price.
We managed to pull off a bare bones display that looked quite striking, was in keeping with the brand and elevated the product slightly higher than it’s competitors… turns out it increased sales by 50% 
It would have looked awful though in any other store I think.
Going back to Richard’s point about putting things in dump bins… there are 2 reasons that play here, one is as Richard said… people like to hunt for a bargain. The other, especially at Ikea when everything in the dump bin is the same product, is there’s the perception (rightly so) that Ikea buys in such vast quantities that these economies of scale translate into cheaper prices for the customer.