So the argument is then over trivial versus non-trivial. In my expereince there are no trivial mutators. Even if they seem trivial at the begging of a project they allow you the ability to move to non-trivial implementations later without rewriting all of your code. I've always read that its good practice not to access your data directly anywhere except in your 'trivial' getters and setters. This allows you to move to more complex storage mechanisms in the future.