Every foreigner who starts to learn Japanese would feel odd why so many words meaning oneself exist in this remote language. Even these beginners will have to decide which Japanese word for oneself should be used. In fact, Japanese often do not include the word oneself such as watakushi or watashi in their conversation. The word seems to be non-essential for one to describe about oneself. That may be the reason for freedom to choose the word for oneself.
When I lived the first time abroad, my colleagues thought that I was the strangest person they ever met. My strange behavior was that I often asked my colleagues about the age of every male researcher in the institute. I had known I should not ask the age of women. I never got satisfactory answer, as they had only vague idea about the age of their colleagues or senior researchers.
Why did I ask? I wanted to decide how I should behave by knowing their age. If they were elder than me, I should be very polite, and if they were younger than me or the sage age to me, I would behave in a friendly and straight manner. This was a kind of iron rule in conducting a proper life for Japanese male at that time.
I was shocked to know that no colleague knew the age of our professor. They were not interested in the age of people.
If foreigners realize that Japanese language (Chinese and Koreans, perhaps too) lacks the words equivalent to brother or sister, they may understand why Japanese are so keen about the age. The language has the words equivalent to elder brother or sister (ani and ane, respectively) and younger brother and sister (otouto and imouto, respectively). But no word that simply means brother or sister exists. We do have the word kyodai or shimai that means elder and younger brothers or elder and younger sisters. The language was really age conscious.
People were always told:
You are elder brother. You should behave patiently to younger sister and brother.
You are younger brother. You should listen and be obedient to what your elder brother told you.
These days we lost this kind of family culture that forms the basis of social atmosphere, simply because people have only one or two children and also lost such attitude. But the words remain, and we still have no word for brother and sister.