I don't think it's worth it for an iPod. It's not "cheap" if you compare it to the price of a new one. In my opinion, I buy an iPod.. if after the year's warranty is up, it breaks, then okay, whatever.. buy a new one.
For a Macbook, however, I absolutely think it's important. Not because "there are so many problems with them" but because in general, laptops are much more expensive to fix if something happens.. and you're generally going to want to keep a laptop working for longer than the year warranty...so it seems common sense to pay an extra $200 or whatever it is for the peace of mind, since there's such a big gap between that and the cost of a new one.