Defending Koichi and Shige
I think I find so many bad remarks on Koichi and Shige that I need to speak up for them.
I keep hearing the terms "nasty", "inconsiderate", "terrible", "heartless" etc. But no they are not.
The good thing about the movie is that it avoids easy categorisation on the children as "big, bad, heartless" creatures, which they are not.
Take Koichi for instance. During their conversations he stresses his parents must have a good time in Tokyo--the only thing he doesn't have is time for them. They were supposed to have an outing, but because of his work (a patient not turning out well), he has to postpone them.
I suppose looking at another angle, it just shows his responsibility--at the expense of his parents.
And Shige, whose brash nature makes her a little misunderstood. Yes, she's a little impatient, but she too have her parents' genuine interest at heart (telling off her father for drinking etc., wanting them to enjoy themselves) Yes, she's pretty outspoken but not in any way that is particularly inconsiderate or grating (at least to me).
Or Keizo who needs to make a living at Osaka.
The problem Ozu highlights I think is that the choice of staying in bustling Tokyo means you will inevitably never have enough time for your parents--unless they know how to take care of themselves. A bit like giving money to your kids and expecting them to take care of themselves.
Life in sea-side Onomichi is never going to be like that in Tokyo. Which is what Ozu is saying.
It's pretty sad, but "isn't life disappointing" (a question I don't agree with) Ozu's answer is "yes, it is."
Note that Ozu, as a person, stayed unmarried with his mother until her death. These questions must have cut him in the heart.