Why are they locking down for a variant that is less severe? Why aren't they accepting this is the best we'll get, and the sooner omicron becomes endemic the better. Rip off the bandaid.
The calculation for China is: inconvenience a small fraction of people, save thousands of lives - even though Omicron is mild, you can still have complications. And China is huge, so a small probability multiplies. They likely prevent millions of cases of long covid. And keep their economy going, where western countries had losses.
Imagine the opposite question: Should they sacrifice thousands of people, and billions of dollars, so a fraction of a percent don't have to spend two weeks in lockdown? Popular support seems to be completely for the lockdown measures. In fact, I think some of it is really over the top (the hazmat suites, the lockdown hotels, stopping a train mid-route because of a suspected contact...) but they do it because the people demand it, not because it is strictly neccessary.