The reason Why Japanese are poor at asserting themselves is ...

It is said that Japanese are poor at asserting themselves.
Largely or partly, it may be right.
I think it's attribute to Japanese Traditional Culture.
Look at this picture.

Can you see any design or pattern in this Kimono?

Perhaps, you consider it plain cloth, don't you?

Actually, we can see beautiful pattern in closeup.

This dyeing technique are called "Edo-Komon".

Many fine patterns exists.

Even now, Katagami(paper stencil) for Edo-Komon  is cut by hand, like this.
Many craftsmen tried to new cutting method by using computer, but they said that computer can't express  sensitive fluctuation.

There are many dyeing techniques of Kimono in Japan, but Komon is something very special for Japanese.

Don't you think why Japanese prefer Edo-Komon that needs to close to see the design? 

I think that an awareness is the most important thing in Japanese traditional culture.

In other words, it may be an interest for the people around one.

So it may be Japanese doesn't need to insist themselves more than necessary for a long time.

With the progress of globalization, we are urged to change our mind. I'm not sure if we can.

The words "Iki" is one of the most difficult word to explain to non-Japanese.

If I had to say, I wonder  Iki is  smartness.

Anyway, Japanese tend to think that the important things are invisible or less-visible. 

I hope I am getting through to you.... 

Sorry for my bad English.