You can't just "swap a font out" without redoing all the work.

Type layout in Japanese in particular has a system of layered, complex rules that include rules that define how to combine Western glyphs with Japanese glyphs and produce visually harmonic work. Swapping a font out due to a cost issue is not workable.

Also, not all pan-asian fonts contain all the glyphs you need to render all the characters you want. A CJK font has tens of thousands of characters, and it wouldn't surprise me if some of these video games will use fonts with particular glyphs that are not always included in other fonts.

Monotype is giving these customers the finger while also ramming a bulldozer in their asses with this change. It's completely unacceptable, painfully rude, and ridiculously tone deaf. In fairness, this is totally on brand for Monotype.