In other words, if they made the battery last twice as long it'd still be equally as annoying (since your daily routine would be nearly the same, except now you also need to remember if it's a charge day or non-charge day).

To be fair maybe 3/4 days buys you some convenience. But anyways charging once a day is a reasonable place to get to, to get something better would require at minimum a 3x improvement which probably means a ground-up rework instead of continuous refinement.

A battery band might get you there but I suspect it'd be too clunky. At best Apple may redesign their watch to support a battery band and allow 3rd parties to make them for folks that need weeks of battery life.