It's safer in a way to guard against these situations, but it seems like they don't intend you to do that often because there are more downsides outweighing it. Proto2 had the "required" feature that had its own issues. Our team trusts to some degree that the user actually read the API spec, and so far it's been ok.

I can imagine message nullness being clearer in languages with optional unwrapping like JS. Like foo.bar.baz gives an error if bar is null, and if you want default-0 you use foo.bar?.baz. Idk if that's what happens though.