I never quite understood the complaints about smartphones not having a multi-day battery life. As long as it makes it from morning to bedtime and charges to 100% overnight, what's the problem? Obviously if it can't make it to bedtime on one charge, that's a problem, but nightly charging makes no real difference. I imagine the watch will be similar. A one-day battery life for a watch is kind of absurd, but it doesn't seem like it'll matter.
One exception to this is people who just never take their watch off. I did this for a couple of years. Having to charge it every night would have been a problem then. I don't know that people do this in large enough numbers to be significant though.
If you travel, it's one more thing to carry. Plus, I occasionally forget to plug the phone in to charge at night. My current smartphone makes it through two days without charging, though.
That's a good point. You'd probably want to carry the charger anyway (unless it's just an overnight trip and your phone lasts many days) but even just the travel itself can put extra demands on the phone, because of time zone changes or watching lots of videos or whatever. A phone that's perfectly acceptable because it can last 18 hours in normal use can cause problems if you're taking a 14-hour flight and playing with it the whole way.
One example is forgetting to plug it in at night and then in the morning the phone is dead. Luckily my phone is more like 1.5 days so I can get by with remembering to charge it at work a little in some cases
One exception to this is people who just never take their watch off. I did this for a couple of years. Having to charge it every night would have been a problem then. I don't know that people do this in large enough numbers to be significant though.