Data classes are "self-documenting" with respect to the "keys" you can expect to be present. Relatedly, they enable meaningful type hints:

  def some_method(input: Dict[str, int]):
    ...

You can just as easily call `some_method({"foo": 1})` as `some_method({"bar": 2})`.

vs.

  def some_method(input: MyDataClassWithFoo):
    ...

Now you can't pass a dict where the key is "bar" and presumably get a KeyError when it tries to look up a "foo" key, you can only pass a MyDataClassWithFoo.