Actually, the OP simply asked "Why did you?" if you go back and read the post.
I answered that with a truthful response. I don't recall there being a prerequisite of having a long, drawn out reasoning to buy this new iPhone to answer the original question. My reasoning was, quite honestly, why not? You can take that as me being curt or "unhelpful" as you called it, but it's certainly just as legitimate a reason as any other one. I didn't need some cerebral rationale to buy the new iPhone. I wanted it so why not buy it?
The OP didn't specify he wanted responses in light of helping other people make a decision, so I gave my reason. It's ok if you don't feel it was a legitimate reason, because it wasn't your decision to make.
:beer: