The Guardian - US

To show that they can.

My betting is we’ll see another version of Monday night’s order emerge once Vought is installed. It will be somewhat more detailed to avoid the confusion of the first attempt. But the Trump White House views the order as essential. It’s part of a much larger plan.

By going big with the first crash, later ones won't be responded to as strongly because 'at least it isn't as bad as the time he stalled everything'. It also flexes the power of being able to do something illegal, even if for a short period of time, with no repercussions.

It was most likely expected to fail by those who planned it, and to me it seems like it was successful in doing what it was intended to do. Intimidate opponents and disrupt foreign relations by showing how easy it is for the office of the president to unilaterally do whatever it wants, even for a short period of time.