Really, there's every possibility here that this thing kills .5% all the way up to five percent or more if the hospitals are overwhelmed and people are left to die at home without any sort of medical intervention whatsoever. Even the lower case estimates are bad enough, and so they really want to keep the lid on this thing as long as possible. The longer we delay, the better we'll understand the disease and have measures in place to slow the spread without such severe disruptions to our lives.

I'm not saying they'll get it right, and I'm convinced they'll get it very wrong at some point, but let's accept that there's a huge risk of failure here.