On the 'About Us' page you would normally show the information on your company.
It is here were you explain to your visitors who you are, what you do, and what you want to accomplish with your website.
Not Important..? Yes, it is.
On this page, in combination with the Contact page you build on the trust your customers want to have in your company before they will do business with you. How long have you been doing what you do, what are your plans, has your company been registered with a Camber of Commerce as is should, are you running your company correctly. That is the type of information the visitors of these pages want to see. They try to get a feeling of your company, try want to trust you will help them, and that trust is what you are building on here.