Deadhippo, I am not Japanese, and I don't think you are either.
You left an interesting message which reminded me of a long-brewn topic; in an international site where individuals from different nationalities come together, there is bound to be some misunderstanding and unresolved issues.
Furthermore, there are only around 1 Japanese member out of 20 English speakers that voted in the "Where are you from" poll.
When a Japanese member may not have had the chance to reply the way he/she deems apt and relevant to the question, I would assume that for a non-Japanese to answer the question on behalf of a Japanese would be to assist and encourage positive communication. When a question has a twist of sarcasm in it (I'm not sure, but it could be interpreted that way, and I am also assuming that that was indeed the way you perceived it, and that you reponded based on your perception.) how would it help either party to reply with another case of sarcasm ?
What are we learning and reinforcing by adding fuel when in reality a better understanding of both sides of the communication channel is called for ?
There are many levels of sarcasm, and I honestly think this was to generate some genuine thinking if anyone cared enough to look into it. There are great possibilities of deep communication. Not looking at those possiblities can seriously limit the relationship by debasement. Wouldn't you like to help in a positive way out of genuine good will for all mankind ?