Let's break this down a little, shall we?
Regarding the amazement factor on performing a simple task such as eating and speaking, it's just something we'll have to get used to. This society will never change because so many people believe that their culture here is unique and that it's viewed as impossible (by a majority) for a non-Japanese born human to survive here. Getting upset, irritated or bothered in any way won't solve anything. It certainly won't make you feel any better nor fix the core of the problem. It's just something we have to accept in this lifetime. Who knows, Japan may be a really changed country in another 100 years or so.
As for other foreigners complaining. This has two parts:
Part A - The resident held hostage: These are the people that are in Japan because their company has placed them here. Some of them are really well adjusted and others live in their little foreign-world bubble. People that complain that there is nothing to do here either don't have a hobby or don't have friends to go explore with. Admittedly, they may just be upset with their current situation. (Some of these expats have their families here while others are single and slumming it... that's a figure of speech before you get your panties in a bunch...)
Part B - The 'here-by-choice' transplant: These are the people who left their home country in search of a different experience or following a dream. Again, some of these people are well adjusted and do well here while others moan and complain about their position in life and in this country.
My overall opinion... some groups of people (mainly B) can simply pack their bags and head home if they are so miserable. The people in group A may have a chance to leave based on their rotation period, but they get a little bit of right to complain and moan if Japan really isn't their cup of tea.
Rarely do I venture to places where alcohol is served, but without fail, I'm sure I can walk into some local Hub bar and hear someone bitching and moaning about something related to Japan. So? Leave already if you're life is so miserable! Life's not better in your home country? Then, no one can save you...........
For myself, Japan is livable. I'm only really worried about the FX market and what that means for onshore and offshore investments.
Rarely would you hear me complain... If I'm complaining, it's because of how much we are getting gouged with airline fees/surcharges. (+ the reduction in baggage if I don't buy a first class or business class ticket. Economy? Ha, what a frigging joke. It was 'ok' when they at least let you take 2 bags at 23kg each....)
Ok, sorry... went on a tangent at the end there.