I agree that Trump's policy execution was terribly flawed.  It unnecessarily impacted many that should have been unaffected.  There is no excuse for  imperfections at the margins of his policy.
But it was not a ban on all Muslims nor all Muslim nations.
It was a ban on immigration from countries with governments that either openly export terrorism or are so unstable that proper vetting cannot take place.  Every head of the main intelligence organizations of our then Obama-led government have told Congress (within the last two years) that we cannot properly vet people from these countries.
We have no business letting more people come here from those countries until we have solved those problems.  And to the extent that those cannot be solved, parts of the ban on immigration should be made roughly permanent.

The Trump administration is going to ultimately clean up this proposal.... and move ahead.  
And when they do, it will be approved by the courts - and a majority of Americans