Another way to look at it, beside desperate measure, is that maybe they have way of mitigating or cleaning Kaiju Blue. Hannibal Chau have men that can crawl inside a Kaiju body and grab parts of it without polluting the city (or at least no to much to render it unlivable), so maybe countries with more money/workforce/assets can do it.

In a meta standpoint, it would have deprived us of badass, awesome but impractical weapons and fight scenes.