This is a GREAT question. It is important that you are updating your site so when your potential customers/clients are searching for information, yours is available to them and optimized to be seen. 

It also helps you when you have steady web traffic, which again, means you need to have the answers being sought. 

In my classes I often use this scenario about web traffic. When I’m traveling out of town and need to figure our where to have a nice dinner on my free night, I usually ask a local. If they give a recommendation, but every single time I drive by that particular restaurant there are few cars in the parking lot, especially at the height of dinner time, I am less likely to visit. Even with a great recommendation, a restaurant that sits almost empty while other similar restaurants have tons of traffic, makes me doubt I am likely to have the best meal ever. 

Even if your website is beautifully designed and you have an amazing company, if you don’t attract any visitors, or drive them there via social media, referrals, etc., then Google isn’t as convinced that you’re a good recommendation for them to give someone via their search enquiry.