The drama surrounding the US »travel ban« underlines the importance of separation of powers. Wikipedia:
Separation of powers is a political doctrine originating in the writings of Montesquieu in The Spirit of the Laws where he urged for a constitutional government with three separate branches of government. Each of the three branches would have defined abilities to check the powers of the other branches. This idea was called separation of powers. This philosophy heavily influenced the writing of the United States Constitution, according to which the Legislative, Executive, and Judicial branches of the United States government are kept distinct in order to prevent abuse of power. This United States form of separation of powers is associated with a system of checks and balances.
This principle will, no doubt, be stress-tested under president Trump.
Donald Trump might be impulsive and be shooting from the hip. This is problematic, as both Democrats and Republicans have granted the President extensive powers. (E.g. killing and detaining people, including US citizens, without due process.)
Those powers ought to be limited. But still, the larger picture is that there is a separation of powers and that the system is working. For now.
And this is where we should be vigilant. President Trump might do stupid and dangerous things. Mainly, these are issues for the everyday political discourse. But if he will try to limit the separation of powers – he will pass a red line. Then, the issue at hand will concern a cornerstone of democracy itself.
This is what is really important, interesting and worrying about the travel ban drama: A new president challenging the separation of powers from start.