The OP simply has got a point. You don't buy a car every two years, you don't buy a sound system every two years, you don't buy a new laptop/PC every two years, you don't buy a TV set every two years, you don't buy a new fridge every two years, hell you don't even buy a new house phone every two years. But somehow, two years is a very long time when it comes to cellphones.
Actually I used to buy a new Windows laptop every 9 months or so. Official reason: I wanted more speed. Actual reason: I just hated Windows.