With over 15 years of experience in the web design/development industray, what I have learned is that while the aesthetics are very important, your website is much more than colours and fonts.
It is your hardest working employee. It drives business - new and repeated. It welcomes people in and leaves an impression. It answers questions, soothes fears and guides your potential clients to the help and support they are searching for. It shows the professionalism and expertise that your clients deserve.
Unless it doesn't, and they go elsewhere for what they need.