I agree with your sentiment regarding resale fixation. However, I have to observe .... "outdated in 12 to 18 months"? I got 31 months out of my S2 42 SS. The only reason I bought into the S3 is because I wanted to. I still have the S0 on a separate charger for alternate use and it still does everything the S3 does (if I have the phone with me, which I usually do). My wife passed her S0 on to our daughter.
To the larger thoughts about resale in this thread, sure, if you can sell it for something down the road, why not? Beats collecting dust in a drawer. OTOH, when it comes to buying these type of consumer electronics, I'd say the expectation should be zero resale value. These aren't mechanical watches. A millions things could happen to completely crater their worth over a couple of years time. To paraphrase a biker saying, 'Get one and wear it like you stole it' If you sell it for a few sheckles on the back side, great. If not, pass it on to a friend or family member or keep it for something different to wear from time to time. Either way, you'll get a couple of good years out of use out of it, which is the real point for getting it in the first place, right?