This is weird to say, but it never occurred to me previously that an ISO-8859-1 font perfectly consistent with all variants of itself + CJK(by switching variants or whatever) would be massively useful. CJK speakers usually switch and mix fonts as needed to build a content than trying to pick single font for everything, and vast majority of people just don't understand multiple languages, so there are little driving forces towards a single universal font solution.

But a universal font makes sense. It's almost odd that this is so rarely said out loud.