I don't entirely blame peoples' consumerism; As somebody who once worked in cell phone sales, the mere act of visiting a carrier store is likely to land you in front of a salesperson who is incentivized to sell new phones and lines indiscriminately. Not to mention the incredible amount of advertising that goes into phones - if people only upgraded when they needed new phones, I don't think Apple, Samsung, or Google would feel the need to advertise the new ones so aggressively.
HN is likely a much more tech-literate crowd than the average person, so I think to a lot of us it seems silly to buy new phones every year. But I know that every time Apple releases a new iPhone, I get a call from my dad asking if it's worth upgrading from last year's model. I say no, nothing has changed, but the next time I see him he has it. Why? Because the salesperson made such a convincing case, not only about the merit of the new phone, but the fact that they could give him such a "deal" on it.