Why write? My friend Dan, many years ago, said such activity could be helpful to aid the demystification of the class as part of the process of encouraging self-activity.
So why write about the budget? Because the budget is a central if not the key element in the organisation of how the state facilitates the accumulation of capital and the general reproduction of capitalist society.
It is then important that we understanding it as part of understanding the world we live in so we can overcome it.