Responsibility,stance,role of TOEIC in Japan

In this world, with English as lingua franca. Learning English is something desperate in Japan. So, showing one's ability of English became so important. Toeic score is one of famous test to assess one's ability. There are popular Eiken(英検）, TOEFL also. Toeic is now so popular. Why not Eiken or TOEFL?? while TOEIC does not have speaking and writing section in test. Is it enough to believe it is showing genuine English ability?? ( Eiken and TOEFL has)
There are advantage and disadvantage of course. First, advantages.
cost is relatively cheap, easy to conduct test because every question are supposed to be answered from 4 multiple choices so this format allows a large number of people take test simultaneously.
This is element other than TOEIC test itself(=Practicality) Next, Reliablity. Basic idea is that if there are two people who has exactly same ability of English should get exactly same score even if each take it in different venue. So, place and audio etc.... should be equal. And this kind of things in TOEIC are quite good.
Next, about disadvantages. It is about validity. validity here means how much TOEIC maximize testee's genuine ability. In terms of this, TOEIC has very big problem. TOEIC has only listening and reading part. No speaking and writing part. Especially, lack of assessment of speaking skill is problem. TOEIC's assumption is, productive skills can be assessed by assessing passive skills. Is this assumption correct??? I don't think so. Being able to listen and read is directly related to speaking ability. This can be explained from brain science perspective. passive and productive ability of brains is completely different.
Now, I've got a question. Why TOEIC became such popular while very big disadvantage is clearly visible. I am gonna do a research later.