[InuTrunks]

B) Not responding is to avoid social conflicts, not (really) to insult the person sending /tell.

To expand on this reason a bit, it's because the Japanese (and the Asian population in general) tend to shy away from any kind of problems that could cause conflict. Also, yes, I understand you can use the "auto translator", but it's horrible way to try and communicate. It's easier to just party with someone who can speak your language.