While I agree with that observation, I also find that the general standards of behaviour of Japanese passengers (not just air, but any modes of transport as well as hotel guests) towards staff and other people have slipped significantly in Japan, compared to say 25 years ago. Since much of that behaviour relates to lack of consideration towards other passengers/guests, I cannot justify it by saying it is due to people's direct reaction to deteriorating service standards and subsequent failure to meet their expectations, but more about the general decline in behavioural standards.
I do see the severe decline in service standards though. The comparison between the JL flight in J 20+ years ago and nowadays is like night and day, although I must say it has improved quite a bit in the last 5 or so years after hitting the real low point 5-10 years ago (I had to write to complain about one of my flights in J in the end because my request for water or tea was forgotten so many times that I lost count and became farcical, even though there was nothing unusual going on in the flight, the meal was awful and badly presented etc - thankfully within a year or two they improved all of those issues).
Sadly the same cannot be said about NH though - the worst check-in experience anywhere in the world was achieved by NH, and that's quite an achievement. It shocked me as it was so unexpected of them (they weren't rude or anything but left me standing there for well over 30 minutes without even a word of apology for their screw-up) and the decline continues...
there have been other signs of bad service on NH since that I experienced, both on board and on the ground (funnily enough, in response to those alluding to the issues originating from the advent of foreign staff, the only good cabin crew member that I came across on one of the NH flights in J was a foreign guy! No, it wasn't due to a language issue at all...).
After the appallingly-handled disruption (and I'm like a disruption magnet who's so used to it that I wonder what's wrong if I don't get disrupted a bit every few months at least) by NH, I no longer fly with them. At least JL has been rather good about pretty much everything so far, except during the bad old years about 5-10 years ago.
Anyway, maybe the passenger/guest stress level has increased because of decline in service standard and resulted in leaving not much room to have consideration towards others and courtesy towards staff. Still, not a justification to be rude or inconsiderate towards others. It's a bit disappointing to see that.