In 2019, if you still have a 2005 website, you are losing clients without even realizing it. It is massively important that your website is aesthetically pleasing and mobile-optimized.
Speed
Attention spans are at an all time low. If your website doesn't load within a few seconds, you may as well not have one at all because people will leave before they even arrive.
Effeciency
With all the modern tools, like live chat and collecting payments, it just makes your life easier to have a modern website.