Paying double down for the term pricing is a bad explanation even if it were a good value. Money is money.
Well, it kind of depends, actually. If you do the yearly iPhone Upgrade Program and upgrade yearly anyway, you're actually only paying about half the increase each year. If you bought the phone outright, you'd be paying the full increase each year, less whatever you can sell or trade it for, which is often a bit less than half the total price you paid, less any applicable fees if it's eBay or whatever. So for me, getting the iPhone X 256GB is $56.15/mo, while the iPhone 8 256GB is $40.75/mo. That's an increase of $184.80/yr (Apple Care on iPhone X costs more, which negates it somewhat). If I bought each device outright with Apple Care, that's about $369.60/yr, and I'm also wasting a whole year of Apple Care that I'll never use if I sell or trade the device. The situation is even better for people who buy Plus models, as the 256GB iPhone Plus would be $45.75/mo, making the X only $124.80/yr or $10.40/mo more expensive. Of course, if you're not the type to upgrade yearly, then it's less worth it. But for some of us it's not as bad as it seems since we are already committed to yearly upgrades.
But yes, it's still an increase, and money is money. But for many of us it's easy to make tweaks to our budget to account for this. For instance, eating out one less time per month. Or lowering our repeating bills. As for me, I switched from Verizon to T-Mobile last March in anticipation of a more expensive iPhone monthly payment. My bill went down about $78/mo (if I remember right), which would pay for this iPhone entirely, a couple Qi chargers, a good case, and AirPods. I've already got AirPods for Christmas, so I added a $10/mo cellular plan to my iPad. Compared to what I was paying before switching, I'm still more in the black than I would have been last autumn. But I get where you're coming from that many people don't think like us being cognizant of price changes over time and making adjustments when necessary. When I get a raise I keep our budget mostly the same, just allocating a little bit more for things such as improvements to our home, my gadget addiction, and our vacation fund, while splitting the rest between retirement, savings, and investments. My point in all this being that I think it's a good idea to invest in the things that you enjoy—as long as you're smart about it. The problem is that many people aren't. Sorry for the long rant, lol.