The largest brands in the world, the FBI, the government, the education system... are all companies that use neuromarketing. It's the best kind of investment.
There are countless reasons why, but the primary reason is that the digital world moves fast. Technology, especially software and search algorithms, are changing daily. Major and minor updates can penalize your site, and cause you to lose massive amounts of money at the drop of a hat. A site that is easy to keep up to date, and user-friendly will give a competitive edge in business. That edge directly translates to your bottom line and overall quality of life.