With roughly 20% of all websites using the framework, WordPress is the most popular content management system in the world. If your business is already one of its millions of users then a custom WordPress theme is right for you.
You should have a website that is tailored to your brand and specific needs. While there are thousands of excellent pre-made WordPress themes available, how you interact with your customers is important, and should be done in your own unique way. With a custom WordPress theme you can accomplish just that and still manage your content using the framework you are already familiar with.
Like mom always said; be yourself.