I don't think it is a big problem given functions like fs.readFileSync already exists. It doesn't have to be a JS standard but be a server-side JS runtime specific function, which can be used when hacks are needed.
The only excuse is that ESM happened during the big Deno Node wars when the community was split, everyone was mad and, apparently making dumb decisions.
I read that a new version of NodeJS has revised require() to bring in ESM modules. That's good enough. (I would prefer importSync() for clarity.)