While I can't agree that iPad Air would be simply better than the rest, but on the actual topic I guess by your standards I don't have. I pretty much get a new phone every 2 years (and thats not cos of any 2 year plans, I buy my phones unlocked). It seems like a pretty decent time span for one phone to me. With my N8 before my Lumia 920 I had it closer to 2? years, as I was waiting for 920 to release. Currently then again I'm sorta eyeballing at getting a 930 even if my 920 is just 1? years old.
But point being, my typical update interval is between 1? and 2? years.
If we're talking about smartphone addiction in general, I couldn't really live without my smartphone. Luckily I don't have to. I don't really know if it's an addiction per se, I feel it's more like there is no reason to not have a smartphone (except if you just dont have the money to spare). While given, it has it's downsides too (group of friends in a restaurant all staring at their phones, etc), but it makes so much things in our life easier. I guess it's kind of like.. if my head hurts, I'll take a painkiller. I have no principle against painkillers, but that doesn't mean I'm addicted to them. There's just no real point in not using the technology to our advantage.