The technological measures on Nintendo's consoles and games are essential for Nintendo to protect its intellectual property from piracy. When those measures are circumvented, Nintendo and third-party game developers suffer tremendous harm because, for example, individuals can then use the emulator to play pirated games. Other commercial platforms have recognized these concerns and. as an example. We understand Microsoft recently took various emulators - including Dolphin - off its Xbox Store
This isn’t an argument about interoperation, it’s an argument about piracy.
In my experience, though there is a lot of lip-service about ‘only playing games you own’, the vast majority of emulator users are playing pirated games they don’t own. This would be a different argument if it was about literally playing Wii discs directly.
[Personally I believe that the copyright terms in computer software like this are way too long, and much (most?) Wii software is really abandonware at this point, and should be allowed to be distributed - but that’s not the law]