In the POS there are times when you want to print an invoice directly through there. For example, if you need to put an order on hold, or a customer is placing a pre-order, and they want an invoice for the products that are on their order. Or if you just want to print it out before the sale completes to get a head start on pulling product. Being able to print it from the POS will make it faster, and is also more viable, especially if there is a user who has access to the POS but not the orders page.
