Batman would be pointless without opposition from cunning arch-villains. Why would Gotham City need him in the absence of the Joker?
In a similar vein, a large part of the rationale for Trump is his perceived willingness and ability to protect otherwise helpless Americans from the world’s many bad guys. He consequently has every reason to identify and build up a suitably scary arch-villain, but he hasn’t succeeded in finding someone to fit the bill. The public is having a hard time buying the migrant caravans as his equivalent of the Joker. Putin, Kim, and Xi won’t work, because Trump actually likes them. ISIS hasn’t done anything interesting recently. Who’s left?
The ayatollahs, of course. Look for lots of demonization in the next two years.