Bob, I wouldn't. If I was really convinced that a product was defective for example, I could imagine getting upset if they were telling me they wouldn't refund it. I've never run into this situation with REI though, with other vendors yes.
Like Justin said, as long as REI continues to accept refunds for defective stuff I'm cool with that. I'm going to buy some BD poles there next month with a dividend, gift card, and 20% coupon. I don't plan on returning them after I've beaten them to death either ;)