Strict immigration controls are a good thing. The people immigrating to your country should bring value, not problems. They should be positioned to contribute to your society, rather than take from it.
Specifically in this conversation, if Japan can use physical AI and robotics to create X goods and services, wouldn't it be better (for the Japanese) to divide X by the Y population of Japan, rather than Y + Z population of Somalia?
The problem is that if you make the place feel very unwelcoming to newcomers because you don't want the people who bring problems, the people who bring value don't come either unless you're offering extremely high pay, which Japan does not.
Sure, take that stricter immigration control. But if people assume upfront that immigrants are intrinsically the source of problems and it takes stricter and stricter controls to filter them down to only those that bring value, this strengthening of filtering will never end.
Remember that one does not _either_ bring value or cause problems. I expect a typical human being to bring some value and cause some problems at the same time. And you can never measure which one is bigger.