Well, first off I think you're being unrealistic about the loss of capacity over time. I've never heard of a battery losing half it's capacity in 1 year, let alone 6 months. Second, there are many ways you could keep your battery charged besides just depending on swappable batteries. For instance, you can get a cigarette charger adaptor so that every time you're in a car you'll be recharging your battery, and you can get a couple of plug in AC outlet chargers to keep in all your regularly visited locations, and the iPod has accessories that add extra an extra battery pack that you can snap on when your battery is running low, so you can get a couple of these and toss them in your car and brief case like you would a replaceable battery, which will bulk up the phone when you have them plugged in, but they're just there to see you through until the next time you're near one of your many rechargers.
Don't get me wrong, I definitely think that not having a removable battery is a downer for some small percentage of people, but it's definitely not a deal breaker. You just need to compensate for the times when you've got a low battery in a different way then you're used to.
p.s. Do you really use 8 hours of actual talk time between charges?