No source for this, but I remember hearing an interesting anecdote some time ago, and I'd love to know whether there's any truth to it:
Back in the 50's or so, when the major American animation studios had a couple decades of experience under their belt but anime was just getting off the ground, some Japanese animators took a trip to Hollywood to learn how the industry worked in the US. They were given a tour of a major animation studio, but through some kind of miscommunication, they came away with the impression that the studio was spending an order of magnitude fewer resources (time, money, manpower) than they actually were.
When they returned to Japan, they budgeted their productions using those lowered expectations, forcing their animators to cut corners and squeeze as much expressiveness into as few frames as possible. Which in turn led to audiences getting used to that style of animation, and created the recognizable Japanese aesthetic that has persisted to this day.
I have no idea, sorry. It would be very interesting if it were true, but it sounds like a bit of an urban legend. Working within the constraints of limited resources seemed to be a constant in all of Japan's pre-bubble successes, from comics, to calculators, so I wouldn't assume there would be any extraordinary reason for early Japanese animators to follow the same principles.
My interpretation was that anime's more limited, stylized animation was due to its direct influence from the prolific manga artist and animator Osamu Tezuka (sometimes called "the Walt Disney of Japan.") All comics, Western or Eastern, must heavily stylize motion in order to have any hope of expressing it in still frames. So having an accomplished dramatic comic artist lead most of the earliest, most influential Japanese animations, most of which were direct adaptations of his comics, working with the low framerate stylized motions that extended naturally from comic book stills, seems to have had a profound effect on the Japanese school.
In contrast, Disney's early animations were inspired by conventional cartooning in subject, and early film and Vaudeville in motion, so given Disney's influence, it should similarly not be surprising that the Western animation school tended towards comedy and fluid motion that attempted to emulate the impression of film.
Back in the 50's or so, when the major American animation studios had a couple decades of experience under their belt but anime was just getting off the ground, some Japanese animators took a trip to Hollywood to learn how the industry worked in the US. They were given a tour of a major animation studio, but through some kind of miscommunication, they came away with the impression that the studio was spending an order of magnitude fewer resources (time, money, manpower) than they actually were.
When they returned to Japan, they budgeted their productions using those lowered expectations, forcing their animators to cut corners and squeeze as much expressiveness into as few frames as possible. Which in turn led to audiences getting used to that style of animation, and created the recognizable Japanese aesthetic that has persisted to this day.