A well written 'About us' is a MUST for any website serious about it's brand and reputation.
There are over a gazillion sites on the world wide web. Your potential readers or even customers have an unprecedented number of options than ANY other time in history.
This means your website must have a page that clearly and simply explains what it is about, leaving no questions in the mind of the reader, while at the same time, convincing them to become subscribers and customers.
A great many websites omit this feature to their own detriment. Having this page can make you stand out as a reliable professional.