The word "quarantine" comes from the Venetian "quaranta giorni," which means "forty days." During the Middle Ages, this was the amount of time ships and their passengers were required to stay in port before disembarking, to ensure that they were not carrying bubonic plague. The conditions on board must have been appalling; even Chris Christie would not force someone to endure such barbaric isolation. But the fact that the New Jersey governor unilaterally ordered a quarantine only proves that he's a panderer and hopelessly ignorant. It does not prove that we shouldn't use quarantine in the war against Ebola. 
Like any medical tool, quarantine has to be employed wisely. It's not a one-size-fits-all concept. It should take into account the behavior of the disease and the behavior of the people who may be infected with it. The guidelines written by Doctors Without Borders seem very sensible to me, and, if followed, should be quite effective. There probably should be some sort of compliance enforcement involved; even the most responsible medical professionals do reckless things at times. But these people should be allowed to go home.
However, the Doctors Without Borders protocol should not apply to visitors like Liberian victim Thomas Eric Duncan who might enter the U.S. for a prolonged family visit and share close quarters with many other people, including children. Of course, such visitors should not be confined to a tent with a portable toilet, either; it would behoove federal and state authorities to arrange for facilities that are more humane and comfortable, not to mention sanitary.
In contrast to Christie's injudicious use of quarantine, there are others who seem to reject it altogether, and in dismissing it, sometimes display a lack of insight or knowledge. Over the last month or two, I have heard comments like this dozens of times: "Influenza kills thousands of people every year, but we've only had one (or two, or three, or four, or five) cases of Ebola in this country..." This is naive at best and disingenuous at worst. All epidemics start with a few cases, and although many (or even most) potential epidemics are arrested or controlled before they actually become epidemics, it's not very predictable at the outset.
This is even true for the current Ebola epidemic in Africa, which was initially thought to be just another periodic outbreak. When there are sporadic cases of any contagious disease, it is impossible to know how far it might spread. If quarantine is to be effective, it should be instituted early, not after the disease has gone out of control. We haven't needed to impose a quarantine for many years, partly because the communicability and mortality rates of various outbreaks did not justify it. In that respect, we've been lucky in the U.S. over the last several decades; public health measures and medical technology deserve a lot of credit, too. But "decades" is a very short period of time in human history, a history marked with multiple devastating epidemics and pandemics. Remember that it has been less than 100 years since an influenza pandemic infected 500 million people and killed as many as 100 million.
No one has suggested that influenza, or firearms, or TB, or any other potential killer should be ignored. So pointing out the disparity between the number of cases of Ebola and the number of cases of other conditions is irrelevant. It certainly doesn't serve as a viable argument against taking aggressive measures to stop the spread of Ebola, and quarantine is one of the best measures we have at our disposal.
There certainly are some optimistic signs suggesting that Ebola can be contained: The nurses who contracted the infection from Mr. Duncan did not transmit the disease to anyone, and by being treated early, had clinical courses that were relatively mild. And in general, the number of secondary cases of Ebola has remained very small. But the fact that we've only seen a handful of cases in the U.S. is not proof that it will be contained. Outbreaks start slowly. Setbacks are possible, and more mistakes are likely. To assume that Ebola will not cause heavy damage is cavalier, if not arrogant. That's why quarantine has a vital role to play in preventing the spread of Ebola. It's just that that role shouldn't be determined by a governor with a history of dubious judgment.