Surely these offers are only any good to people that were going to change anyway? I read a lot about people who are changing their cars just to take advantage of the deals, but they will be spending money, or getting further into debt when they otherwise wouldn't be.
To me, it's no different to your wife coming home with new shoes, saying she had to buy them as they were in the sale, even tho' she has a cupboard full of shoes already.