I don't think there is much to gain from intelligent Japanese people from becoming fluent in English, other than maybe leaving the country. They can already make a good living by climbing the ladder in a large firm.

It is unrealistic for the average person in the country to become fluent in English reading/writing - lots of people are barely literate in their original language. Even if everyone became more skilled and wealthier, what would that achieve? Import more junk from overseas? Increased wealth will just be funneled into land or spent on smartphone games and prostitutes.