Others have made this point but I'm going to chime in. Yes, many people who get this will not show much in the way of illness (or may not realize it). The elderly and those with health problems are most in danger.
The issue is containment and "flattening the curve". You can't have this very contagious virus start overwhelming the hospitals and available health care professionals. This isn't a joke.
And it is showing the US that our absolutely unprepared health care system couldn't handle a real emergency. What if this was just as contagious but also as deadly as SARS or, heaven forbid, ebola. Can you imagine how bad things would be if it were? Sacramento County can't test more than 20 people a day, and they are devoting that entire capacity to checking the folks in Elk Grove at the center where the victim passed away recently from this virus. So, everyone else in Sacramento County can't even be tested - it's not possible. At all. I have a friend with a 100° fever and symptoms who went to the doctor today and he can't get tested.
Consider this our wake-up call. What if this were an intentionally released bioweapon instead of a somewhat benign flu-like (but still much more deadly) virus. We are screwed. I'm not getting political, I'm just saying we need to reconsider how we prepare for these things because as of right now, we aren't. At all. Other countries figured this out. We need to as well.