I can't soeak for anyone else but for me it was because I'll get a 10% discount off of out of pocket cost. 5% from the target red card and 5% from a pharmacy rewards coupon. And yes I have confirmed that both of these will be accepted for Apple products.
But I may be SOL regardless. As I've said before on this thread I'm buying off contract at full retail. People on this thread told me target wouldn't sell them of contract and I called and confirmed that is true. But, I specifically mentioned to the rep at preorder that was my situation and he said okay and got me a preorder. So I'm going to play dumb and if that doesn't work raise hell and hope they have a way to it in the computers that doesn't require a new contract. Because if the guy had told me that when I preordered I would've made other plans. Dicey situation at best. But I'm holding on to hope!
they do have a way to sell it in the system. Trust me, I know. there is a DPCI for it. find out what it is, and when they enter it it will be the full cost. If they tell you no, tell them you know there's a DPCI in their storage locker they keep the phones in.