It doesn't take a lot of research to realize that the human eye is drawn to attractive things. So the better looking your LinkedIn profile is - meaning professional and complete - the more qualified you'll appear to your audience and the more interested people will be to check out your site.
When it comes to building your business and developing a powerful network, you'll want to develop a reputation as someone who highlights others. Not only does this give credit where credit is due, it also communicates that you're secure with your success and have the ability to promote others in your industry.