We want the systems we depend on to do what we expect and need them to do.
A useful component of such systems is that there is a basis of expectations, principles, and boundaries that exist before and after we encounter it. The drawbridge works because of the rules of physics, not because an invisible pixie decided to open it at this moment.
So there are two kinds of situations. One where we are dealing with a predictable system of expectations of how and why things happen, and the other where explanations can be suggested by fact but it is justifications, not explanations or principles. In the irrational system, explanations are often made after the fact and changed as soon as they are examined.
Both kinds of systems make up our world, but the first kind, the civilized, efficient, mature kind, is the type we can build our world around.
We can set the rules and play by them. We can outline a theory and prove it.
Principles are really important in the moments when it’s really hard to stick to them.