Ignoring whether the new rules are reasonable, the most baffling part of all this is how small the foreign population in Japan is.
Things are undoubtedly harder for the average Japanese citizen these days, but foreigners make up just 3% of the population. Targeting this cohort, I can't imagine a single policy change that would positively impact the lives of non-foreigners. Even if you snapped your fingers and deported every foreigner out of Japan, the only noticeable impact would be a shortage of low-wage workers/convenience store staff, who are predominantly from SE and South Asian countries.
The foreign population growing from 3% today to 10% in 45 years should be a consideration for sure, but the amount of attention and media play immigration issues get in Japan is astonishing. I don't think the politicians are acting in bad faith, so my conclusion is that they simply don't know what else to do to improve things.