As someone who went through the US immigration system, I'm dismayed at Trump's mishandling of immigration. As appalling as it is to shut the door on refugees (who certainly aren't here trying to "take-yer-jobs!") I think the more disastrous part has been shutting the door on *legal* green-card and visa holders.
There is a certain contract - you, the immigrant, will pay thousands in fees, be subjected to all sorts of paperwork and background checks, and will suffer with a life on hold (and possibly be trapped working in a company you don't like, but can't leave) and in exchange for that necessary evil, the US will process your application as quickly as it can and either accept or reject your stay.
However, to then take people who have gone through that process and to lock them out is a complete violation of that contract.
I'm pleased that the outrage has been this acute, and I'm pleased that the White House has backtracked on the green-card restriction.
Oh, and, not for nothing, I'm not at all surprised that Trump made sure the ban doesn't touch any countries that he does business with (from the left-wing rag Bloomberg).