Depends on your definition of 'all day'. I wear mine from about 7 or 8am until about midnight and it just about lasts that entire time. It's a series 6 so not the newest either.
I guess if you want to wear it to sleep it just means taking it off sooner to charge. Personally I hate wearing it to sleep, it feels very uncomfortable and bulky for that.
The sleep thing is important IMO. That's extremely useful data to have. Feel tired? Check your sleep then remember what you did the day before to mess it up (drink/bed late/eating etc). Trains you to sleep better which is the most important thing in a productive life. But Apple watch doesn't make it easy to do both yet.
I guess if you want to wear it to sleep it just means taking it off sooner to charge. Personally I hate wearing it to sleep, it feels very uncomfortable and bulky for that.