It's important for two reasons. One, it allows the government to have fiscal credibility. It's a clear statement about where fiscal policy will be headed in the future. That's probably the main reason.
The second aspect is that it makes the job of the Minister of Finance easier because, as one can easily imagine, with the Minister of Finance announcing in the update that there will be a stimulus package worth between $70 billion and $100 billion—“but give us your great ideas”—the Minister of Finance will be put under tremendous pressure. Having clear targets allows the pressure to be taken off to a certain extent by making it easier for the Minister of Finance to say yes to priorities, and no to other proposals because that would steer the government away from its fiscal targets.