The OP and people like him are how Apple and many other companies have essentially figured out a way to put a siphon into people's bank account. Under his scenario, he is sending money to Apple on a monthly basis simply to have the latest and greatest, and not only does he have ways of rationalizing it, but he will fight others that call out his rationalizations. This is the world we now live in.
OP, you are paying full price for your phone. Actually, considering the resale value is often higher than the trade-in, you could be considered to be paying more than full price if you trade it in. Yes, monthly payments soften the blow, but the damage is the same. I once was like you, and after this year have decided that this yearly upgrade cycle is ridiculous and not worth it. I honestly believe no one should upgrade yearly anymore. The prices have gotten to the point where you are just pissing money away.