When designing a website, it is important to think about product awareness and how the visual presentation will impact a user or potential customer.
Just any old website design won’t do. Neither will that website that you launched 10 years ago. Users want, and demand, modern website interfaces. A modern design shows that you care and that maintain and update your website and content regularly. (Even if it isn’t, a modern design will give this impression.)
Grids are an essential tool for modern web design. In a reality that expects user interfaces to function and look great on any number of unknown screen sizes, the grid helps create a “one size can adapt to all” final product. This further manifests itself into quicker launches, predictable budgets, and an overall better product for most projects.