Originally Posted by Ambrose Bierce
When the item in question is owned for longer than the life of the battery then this will be an issue... right now the lifespan of the device does not call for a replaceable battery.
I agree 60%. LOL. In reality, my several year old iPod 5g, which got used hours and hours per day is still going strong on its original battery, and never ran the battery down during the day where I was without function. That's a strong argument for the "don't need a user changeable battery" in iPods.
My iPhone, on the other hand, is a different story. The battery life on it, if you do a lot of surfing or are in areas with weak signals, is abysmal. I more than once got the 20% battery warning, 10% battery warning, and then dead phone (all within a few minutes!) back in the early days. Then I learned you just had to keep a charger in the car, and on the desk, and keep the thing plugged in whenever possible. A pain, but do-able.
A "spare" battery has the advantage of "change and go", not "wait for a charge and go", and is small enough to keep in your pocket where ever you are. Not true about a USB port/charger.
Battery life was such an issue for me, I jumped on the Mophie Juicepack when it became available. It's been a real blessing on occasions, keeping me on the road, albeit with a bulkier phone, when in the past I'd have been dead-battery city.
edit: someone above asked if anyone has ever seen someone carry a spare battery and change them in real life. YES. ME! With both my old Razr and my Treo 700P. It just depends on how much you use the device during the day, doesn't it?