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.
Japan's culture doesn't take well to immigration, but Canada bars many immigrants or even visitors on the basis of DUIs - I don't have a DUI, and I'd have to jump through many hoops to migrate to Canada regardless, but nobody can earnestly say Canada isn't receiving many, many (too many?) migrants.