When the arguments were being made at the lower courts, in some cases, they were streaming online. I recommend you go and listen to it. I did. It was about an hour and fascinating. You got to hear, directly from the government lawyers, why this was necessary and from the other parties why it was just another version of the Muslim ban. 

A couple of the interesting parts:
1) The government lawyers were given the chance to describe the dangers faced by the US that required this ban. Basically, it was a chance to explicitly say why this wasn't a Muslim ban. They flat out admitted that they couldn't prove that there were  new dangers that required new protections. Listen to it for yourself, it was a weird admission.

2) Another interesting discussion was around if it counts as a "Muslim" ban if it only affect less than 20% of the population. An argument the government made. Led to a fascinating discussion on if a ban only counts if 100% of the target is affected.