You want your company to endure. To go the distance, it will need to have a distinct sense of purpose, and loads of personality. You want customers to get to know, love, and remain loyal to your company’s personality, as they would an old friend. And old friends generally remain constant; they don’t chop and change their personality or do unexpected things. So you need to make your brand messaging consistent and repeatable so your customers continue to know and like what you’re about – this is what brand voice does.