For some people, they just use a free website maker and use their designer to make a theme. Most don't realize the powet that CSS has, and how it can really change their site. Do you use CSS on your site? If you weren't using it originally, how has it impacted your site's look and feel?
I was blown away by how much of a change CSS made on my site after using it. It looked much cleaner, and I just felt like I had more control over every little look.