Four percent seems like an acceptable number to many people, though it's little over twice as high as the flu (about 1.5%). At 4%, that's just over 338 million deaths globally. Just over 23% of the 583,000+ deaths so far are in the U.S. The virus has mutated again since arriving here, becoming more contagious, though doctors are feeling more confident about treatment options. Of course, percentage of fatalities could go up, if the hospitals get overwhelmed and have to make the hard decisions about who gets treatment and who doesn't...
Personally, I have my own perspective about WHO's motivation from reading news reports. Contact tracing traced the A virus (the 3 day bug, before the first mutation to the more deadly B virus) back to Guangzhou in September 2019, near a U.S. NIH lab that was studying viruses until August 2019 when they were forced to shut down because they were having difficulty disposing of the viruses. I was watching traders in China on social media posting about this virus as early as November 2019.
One death is too many if it's one of my loved ones. But I never said we need to shut the entire economy down. People need to take it seriously and be sensible and more diligent. Why not err on the side of caution?