like I said, it's a matter of preference. For my usage pattern it makes no sense.
For me keeping track of extra batteries is a far bigger hassle then plugging in my phone, especially considering I'm usually sitting at a desk all day. It's not worth it for me to worry about extra batteries for that once a year when my phone might die on me at an inconvenient time. If I was more mobile and had my battery run out on me often it would be a whole different ball game.
Of course this applies to my cell phone, for my camera you're probably right, I need to try the 2nd battery route, I'll probably be converted.
I guess I was applying my phone mindset to my camera without really thinking it through...