In my view of government, legislation is a compromise among different interests and people, assembled by politicians to get a majority of votes. Some laws are narrow in focus and effect, often driven by one or a few politicians under the stimulus of a narrow and small group of fervent believers. Think perhaps of an earmarked program for research by NIH on an uncommon disease. Call these the laws of passion. Other laws are broader in focus, meaning more politicians came together in a compromise, often through judicious backscratching and logrolling. Call these the laws of interest.
Once legislation is enacted, and appropriations made, there develops the familiar iron triangle, of bureaucrats who administer the law, the interest groups supporting it, and the legislators who derive votes from passing and maintaining it.
As time passes, technology changes, and society changes, some laws lose their relevance, or become a misfit with the environment. But because people are creatures of habit, it's easiest not to rock the boat.
I can argue that there's value to having a Trump come along with a drastic budget proposal simply because it forces the reevaluation of existing laws. Is there still a valid coalition backing the law--does the old combination of passion and interest still live, does it still have the clout it had back in the days of creation?
I'd compare the situation to moving: a family buys a house and gradually fills it with things. Time passes and they need to move, to downsize to an apartment. Then you discover which things are useful enough to take to the new place and which are not. Or maybe instead of moving to an apartment you need to move to a McMansion.