It is pathetic that those people were able to circumvent the travel ban so easily.
However, if one believes the statistics, the CFR (Case Fatality Rate) of this disease is 10 or 20 or 30 times worse than the common flu, and because of our lack of immunity to this, containment is needed. This is the expert opinion of every single virologist and epidemiologist who has chosen to opine on it. Some countries have disregarded those warnings knowingly or unknowingly, and the results can be seen in Italy and Iran.
This is at its heart a mathematical and statistical game. The virus will expand at a certain rate, and increase infections and deaths at a certain rate that exceeds the flu. One must figure out what to do about it, and each country has chosen extremely constrictive containment measures at great political and economic cost.
All of these are facts stated not by politicians and media figures, but by medical experts (virologists and epidemiologists) in the major countries. The politicians and media figures are repeating what the medical professionals are saying about this. So this is not driven by politicians, but rather by medical advice.
I agree, but the numbers you appear to be relying on are based on incomplete information and worst case scenarios. So far in almost every case the more complete the information, the less serious the numbers indicate this issue will become. The expert virologists and epidemiologists that you believe all support your catastrophic view of this problem typically do not, but they are very cautious about how they word their opinions and of course most of the media seek out those who are willing to make shocking yet unlikely predictions.
It may be more contagious than the flu largely because it has a long incubation period and approximately half of infected people have no symptoms and another 30% have symptoms that are so mild that they are able to ignore them, so people who are contagious to others. It may have a higher mortality rate than the flu, but we really do not have enough good information at this time to know for sure. More accurate numbers will become more available as time goes on, but we are still going to have people in charge of compiling the numbers who have a vested interest in not showing that their predictions were wildly exaggerated. I can tell you that the medical professionals that I have talked with personally mostly have a point of view that is fairly close to mine.
We have the example of Italy which has the oldest population, the worst run socialized medical system and the largest number of recent Chinese immigrants in all of Europe. They do not have enough ventilators to go around so their triage system denies life saving treatment to the old and people with medical histories that indicate they have poor chances of survival. It is a death sentence. There are many reasons why Coronavirus has spread more quickly in Italy than in other areas.