In my experience, the immigrants and foreign workers in Japan in the highly skilled jobs often don't need much Japanese to do their jobs, but the ones that learn the language have a much easier time and obviously advance quicker. All the people I came in to contact with low skill jobs that had spent any time in Japan, had amazing Japanese because they absolutely needed it because the vast majority of people do not speak any meaningful amount of English.

Japanese is not an easy language to learn, but its not impossible to learn. If people are allowed in then they will learn Japanese