Just because some people want something that doesn't suddenly make it reasonable or wise. In this case it's a problem for many already successful people living in Japan currently who will be forced to leave. It's also a problem for Japanese companies who have hired those people or who want to attract foreign talent to positions that pay well, but don't typically leave someone fabulously wealthy compared to most of the people living around them. It's also a problem because the policy is coming in at a time of increased xenophobia and overt racism and while this policy is likely to reduce the total number of foreigners living in Japan, it's unlikely to address the problems people have with the foreigners who will remain, and it could actually make those problems worse.