maciamo, reading this all [starting from your original post up till here] was indeed very interesting, and pointed out well most of things i noticed when being in japan as well >.> yet i never [ever... and i worked with people, basically talking to them, as i was a waitress in a quite noisy club] noticed the 'food money sex' topics you've mentioned. sex- it happened to pop out in a conversation a couple of times, money never. salary man talk about their work thou [yeah like they have other topics, while their job is their essence of life, why would they tlak about anything else..] i never talked about food, except for when my landlords invited me to the restaurant- short talk basically about my likes and dislikes and differences between food here and in my country. that's what i'd call normal actually.
you mentioned weather >.> i also think it is for them a way to start a conversation, but i noticed that also it makes up for a short nice talk between neighbours or people who are somehow related but not too much. at tenis court where i have been using internet, the -only- topic of conversation between the adults was 'atsui desu ne..' 'neeeee...' or 'suzushiiii' when entering etc. [what actually surprised me once, was that when the temperature dropped like 3 degrees they suddenly started saying 'samui desu yo ne...' X-x; queer.]
as for the rest- agreed fully. i think i understand your point about saying things that they cannot be praised for once. when i went to japan i of course wanted to see how great it was, but mostly because of what japanese culture scholars keep saying about the country, i wanted to point out the bad things instead. most of those from my university after 2nd year become japanophiles and see it as a pure paradise and the japanese as almost divine, everything best. quite annoying after four years. i wanted to see for myself that they are only human and also like everyone else have failures so i made an anthropology of my own study on japanese this summer

i also would like to ask you a couple of things myself, i think they fit in the thread-
firstly, how about club culture making their shalowness stronger? it shocked me to see how two guys i recognised as friends once ended. they were coming with other friends to the club every saturday, and every time they were getting drunk, also used to fall asleep inside. and once the more rational guy, who never got that drunk and never felt asleep in the club, decided to leave earlier, without his friend- we couldn't wake him up anyhow. so he called for a call-girl [and a boy, who was her bodyguard or whatever, i don't know] to guide him home when he awakes. i was shocked, what a friend does that... i can't imagine anything like that happening in my country, not all europe- maybe in france it could happen, but definately not my area.
even more shocked i was when they both showed up like nothing ever happened next saturday, while on that night the guy who was left behind had a breakdown and cried later [also probably % made it easier for him...].

second thing, maybe not about the shalowness- the bodies... you know the party people sleeping on the sidewalks? or in the park... when i first saw a guy sleeping half in the bushes half on the sidewalk in front of yoshinoya, i thought he was dead... nearly jumped of my skin... but he snored >.>;;
also it's not only party people- some high ranked ceo, and one of them who was my aqquaintance, share the same habit of sleeping on the sidewalk, even if their house is like 10 minutes away. whyyy? x_x; it is obvious that they absolutely don't care... is it the stress? the ceo's do reaaaally weird things when stressing out. is it maybe one of them?