Why don't Asians speak their mind?

The Sushi Man is always posing this question to me. I attribute it to:

1. Asian culture of being non-confrontational.
2. Chinese saying "Those who know much, talk little".
3. Being frank pisses people off/irritates them.
4. They don't give a damn because they feel that their opinions will not be accepted.

I can list an example by summarising an IM conversation I had with a friend.
Friend: "I'm thinking of quitting."
Me: "Why?"
Friend: "I feel that I am underpaid."
Me: "Ain't we all? I feel that I'm underpaid as well."
Friend: "I don't want to talk to you." *pissed*