Ultimately I charge my phone (almost) every day, so I'm sure I could charge my watch every day as well. But it's still another habit I have to build, another way I have to adjust my routine to accommodate the things that are supposed to make my life easier.
The other thing is, battery life degrades over time, which is relevant if you don't want to be buying new devices every couple of years. When I got my Garmin it probably held a charge for 6-7 days. After four years, that is probably closer to 4 days, which is still pretty good. If less than a day is the starting point, I can imagine that after 3+ years the battery life will be poor enough that you regularly end up wearing a paperweight on your wrist for some portion of the day.