Testimonials are so horribly, inexcusably underutilized. Reminisce for a second on the last time someone told you about how absolutely, ridiculously amazing a product was. You had to feel at least slightly inclined to check it out, right? Maybe at least do some stalking online to see if it's something worth your time? Hearing praises straight from a real customer increases your chances of purchasing a product by 400% (according to a study I made up just now) and you can take that to the bank.
The Power of the People
If you offer an amazing product (let's hopefully assume that you do), you might at some point experience some frustration in getting the word out. You have amazing catalogs outlining your products, post on social media four times a day, and have mounds of informational content on your site outlining the incredible benefits your products offer over competitors.
The problem is, everyone else is doing this too. You have something special, but all of your competitors are thinking they have something special too. So a customer researching a particular product across a number of different websites has the potential to see a lot of the same information. And you have the potential to accidentally show the same information because, after all, your products are awesome and you want the world to know.