If it's a no questions asked return policy I am not sure it qualifies as "fraud." Unethical maybe, but not illegal. Regardless, I think this behavior is likely pretty rare and hence not a concern to Apple. I mean, what a PITA to purchase, unbox, and set up a computer only to wipe the HD, rebox it, initiate the return and lug it up to fedex/ups 28 days later. I wouldn't bother with the hassle, I'd just wait a month to buy and see what happens if a refresh is expected.
That being said, if I did happen to buy a new iMac and had no idea a new model was imminent (which doesn't happen, because we all read macrumors, right? 😉 ), and that new model released within the 14 day window of my purchase, I wouldn't hesitate to return it for the new one. I'd tell Apple exactly what I was doing and they would happily do the swap. With the margins on these computers they can make those swaps, sell the "used" computer as a refurb, and still make money on both machines, plus keep a couple happy customers.