It's not so much as what Apple think but were Lith-ion battery tech is. We can't have it all and it's a compromise until there is some new type of power supply/battery technology.
I can only speak for myself. I charge my iPhone and iPad every night so it will be beneficial to me to do the same with the aWatch. If it were 2 or 3 day battery life I would probably be wearing it during the 2ed day when it went dead. Better for me to have a daily pattern of charging until battery life could be extended to over 1 week of real life use (probably at least 5 or more years).
If Apple offered a nice charging stand and showed how simple it was to take the watch off before you go to bed to charge it I don't think it would bother many people. Except for those who need sleep tracking. One question I have is, how long does it take to charge? i don't think anyone has speculated on this yet.
I still think this might be like the iPod and within a year or two a shuffle or nano type device that is more geared towards just fitness. Ben Shaffer, who was a shoe designer at Nike now works for Jony Ive. Jay Blankin also worked at Nike in the division that created the FuelBand. Plus they've hired doctors and others in the medical devices space in the last year. I have a hard time believing the fitness component they announced with Watch is the be all end all of their ambitions.