Websites are constantly evolving. If they didn’t, sites would look exactly like as they did in 1990. New technologies and designs emerge regularly and as the internet changes so should your site. Users are accustom to these changes and these start to become “industry standards” or “best practices”.
The more in-line with how the majority of sites are designed and function – the more receptive your site will be in the eyes of the visitor. Outside of performance – design and functionality of a site is crucial to a websites success. Once of course you’ve brought visitors there with your optimized content, social and/or media buys.