She had a visa, but perhaps she should have been further vetted, yes?
[1] https://www.nytimes.com/2015/12/13/us/san-bernardino-attacks...
Edit: that dodges the main point. A better response would be, the other attacker was a US citizen, does that then make a good argument for banning US citizens from entry?
This woman was from Pakistan which suffers terrible internal terrorism problems. While the government of Pakistan is great, there is obviously a terrorism problem in that country. It seems like perhaps that would be grounds to make Pakistan another possible 'country of concern'.
The migration halt inconvenienced 100 or so people, but it has had a much bigger (almost positive) impact in ways people are ignoring so they can call Trump Hitler.
He isn't exterminating people, he just said "look this area of the world is in crisis, we don't want that here so stop coming" and this is making everyone else pull up and start doing stuff.
That seems like its doing some good, and isn't just "outright evil" as you called it.
A case might be made for shutting down new refugees from those countries, or even new non-refugee visas. But there's no sane case to be made for keeping out people with green cards.