[cesarb]

> Think Java: for each type you have to create a new file.

That's untrue, Java has inner classes, and they can even be public. A "public static" inner class is nearly indistinguishable from a normal top-level class (the only real difference is that its name in the bytecode has a $ character separating the names, that is, its name in the bytecode ends up being something like "org.example.Outer$Inner").

[valenterry]

Well, you still have to define them inside of another class then and have to find one that makes sense. They also have an reference to the outer class which might not be desirable.

That being said, it maybe makes it slightly better, but I hope you agree that this is still very much a supoptimal solution and probably comes from a time where searching filenames was the best way to navigate code in the lack of modern IDEs.