I have a Samsung Galaxy S4. It's mine, I paid for it, it's unlocked on Ting. Bill runs about $30/month. I use it to check email, text, make phone calls, play music and be a GPS with Waze. I do use it every day.
What does a S5, S6, S7 or latest iPhone offer that would make anything I do *that* much better? I went from a iPhone 3GS to the S4, which was a huge leap in screen size, processor power and other things. That 3GS is still used by my kids. But my wife has the S6, and yes indeed it's a little prettier and a little peppier but it's not worth even a dollar a day.
I mean, if it gets run over in the parking lot, I'm going to get something newer for sure, but honestly, why spend money if I don't have to?
Phones are rapidly approaching where PCs are ... the new models look like the old models and are only marginally better. Much like other things sold as fashion, you can tell that the newest phone is a "want" rather than a "need" by the amount spend on flashy and sentimental advertising spots. You don't see ads for lettuce, carrots or cucumbers because there isn't a need to create a market for those things, as they actual needs. With phones (like cars) you pick up last year's new model for a fraction of the cost and let someone else take the depreciation.