When dealing with a viral outbreak, whether it be chickenpox, measles, the flu or any other virus outbreak, the proper containment of the outbreak is the only reasonable and responsible course of action.
When you were a child and contracted chickenpox, did your mother send you back to school to infect all the other kids?
No, you stayed home until you were no longer contagious. Same thing here with Ebola except that it's far more people from a particular region of Africa.
So yes, the US should put a ban on all visas for travelers from those regions of Africa. Or perhaps a mandatory 3 week quarantine at the source. Why keep importing Ebola? Or at least why keep importing people with a high risk of being infected with Ebola?
Some are saying that the entire state of Texas needs to be quarantined now. That is ridiculous. 2 isolated cases from a known contact source does not an outbreak make. 10, 20 or 30 or more, most definitely an outbreak, especially if it can't be traced back to a contact source. Talk about walking around in a mine field.
Now if there is a larger outbreak in Texas in the next three weeks, if the fellow travelers on the second nurse's airliner generate outbreaks to wherever they've gone to, then it's going to get really serious really fast. Marshall law serious. Forced quarantine of entire areas serious.
But, thankfully, that spread and that outbreak has not happened yet. There's a chance that it might. We'll have to see.
You can read all about it: The Hot Zone: The Terrifying True Story of the Origins of the Ebola Virus: Richard Preston: 8601401254928: Amazon.com: Books