Most of us don't need to write the CEO email ever in our life. I assume the CEO will write the flu message to his staff in the same style of tone as everyone else.
For contrast:
"All: my daughter is home sick, I won't be in the office today" (CEO style)
vs
"Hi everyone, I'm very sorry to make this change last minute but due to an unexpected illness in the family, I'll need to work from home today and won't be in the office at my usual time. My daughter has the flu and could not go to school. Please let me know if there are any questions, I'll be available on Slack if you need me." (not CEO style)
An AI summary of the second message might look something like the first message.
I know what you are trying to say. I agree that for most emails that first tone is better. However when you need to send something to a large audience the second is better.