For the same reasons you spent time decorating the walls in the dining room, putting accent lighting outside and made sure that your waitstaff’s uniforms looked ‘just right’ – you need to spend time to develop a great website, not just use a $5 template you found online. Why spend time and money doing all of these things when the customer is already there, but skimp when it comes to getting the customer to your doorstep?
A great restaurant website design is crucial in today's market. Not spending the proper time to make your website look sharp will degrade the perceived value of your overall brand. Or even worse, not having a website shows that you aren't interested in marketing to a new audience, getting found or being discovered.