The last thing that I need is yet another device that has to be frequently charged. My phone is bad enough, thanks very much (and I have to charge that every other day). Although having to charge a watch daily is not disastrous, it is a big enough pain that once I tried the Pebble, there's no way I would go back to something with a shorter battery life. Here's the advantage: I never have to remember to charge my watch at all, because it warns me a day in advance that a charge will be needed within the next day. It's nice to not have the cognitive load of remembering the watch -- it helps it to seamlessly integrate into my life.
I totally get that lots of people wouldn't care, but I do. Once I experienced only having to charge it every week or so, that ability became a dealbreaker feature for me. A watch that I need to charge daily is a watch that cannot accomplish what I want it to.