In practice, I charge my phone when I go to bed. So as long as the phone lasts for the day's usage, I'm all set. (I don't know how long Android phones' battery typically lasts.)

My N1 is fine for two days, the third day it becomes risky.

I've yet to know a smartphone user who didn't have to worry about battery life and never experienced their phone dying when they needed it. Being able to have many options for putting your phone into a lower power configuration (turning off 3G, changing screen brightness, maybe even changing the screen color) seem pretty useful for those not so rare situations where you need to stretch battery life.