We're also visual beings. Once someone told me that we're actually going back to where we started. For a long time in human history, we were visual beings; in the 19th Century texts, especially in newspapers, became dominant. Today, with the new media, with the easier way to take pics, record videos, draw infographics etc., the images are again becoming more and more significant.
We're charmed by beautiful things. That's why we are attracted to beautiful design.
That's why I think the quote: "People don’t come to your website to look at your logo or navigation, they are there for your content," is partially right. Yes, content matters. A lot. Without valuable content, your site can be the most beautiful in the world, it still wouldn't matter much.
On the other hand, great content deserves and needs awesome design to highlight that great content.
Basically, content and design are like a happy, loving couple; you must not see them as separate entities, rather they complete each other.
Develop them together.
That's why it's so important that a designer and the editor/author are partners!