You seem to think that it's talk time that is eating my battery, it's not. I do have a bluetooth headset, and I might spend a couple of hours talking on my phone some days, but that is not what kills the battery.
What kills my battery is the screen on time. That's because I use my phone as my main mobile computing device. If I'm in a meeting, I'm using it to read relevant documents, or viewing a slide deck. The rest of the time I'm sending/receiving emails and IMs. And aside from all that, if I'm sitting around being bored then I use it to check facebook, shop on ebay, play some game, or log onto terb. In short, the screen winds up being on a LOT, and this is what kills the battery. I can see in the power status page that 80-90% of my battery goes to power the screen, and that's because any non-talking use of my phone has the screen on. Everything else the phone does uses very little power, but those nice bright high definition colour screens are power hungry.
If I just used my phone to talk, or left it sitting around in standby mode, the battery would probably last a couple of days, but turn it into a mini-laptop and use it for documents and emails, and suddenly you're into hours of screen on time, and that's a killer.
And yes, I think those cases are BULKY. I carry my phone around with me in my pocket. I carry the spare battery in my back pocket and I have another one in my laptop bag. Either way it's not nearly so bulky as the battery case. Sure, you can probably work around this iPhone failure by using that case--but it's an ugly and stupid solution that reduces the convenience of the phone. All for what? Because your iPhone case is screwed shut. Stupid.