I think they also are required to sell a certain number of extended warranties or else they are considered not to be doing a proper "job".
I usually just say "Well, when this dies in 2 years, I'll be buying a new one"...considering some of the warranties ended up being 30%-50% of the actual price of the item, they usually aren't worth it.
On top of that, have you ever tried bringing in a busted item and dealing with the customer service?
Having said that, an ex of mine had a warranty on her laptop and it got replaced twice with newer models as well as the warranty being extended to cover the newer computers. Took a lot of haggling and annoying them constantly, but it can be useful on some items.