Watch for patterns and threads. True, no response is required. But within that context, you might find that people tell you more. If they feel that nobody is going to hold them accountable for what they write, they may well be more open with their opinions. Read all that feedback carefully and you may discover things about your site that need changing.
Feedback is fundamental to the way the web works.
So it makes sense to facilitate it and encourage it. Give your visitors permission to yap back. And listen carefully to what they say. If you're looking to increase conversion rates at your site or make your emails and newsletters more personal and interactive, Nick's your man. Voice your opinion.