Product and design go hand in hand. At the end of the day great design is a big part of having a great product. A beautiful and functional design makes a product exponentially better. Some examples of how design has driven product and product growth you can look at companies such as Fab, Path, Pinterest, Foursquare, Tumblr, Twitter and Instagram. All of these platforms on both web and mobile have implemented beautiful and unique designs. I am not saying that having a good design will make a terrible product better, but a product that has a beautiful aesthetic and a clean UX can go a long way in driving growth.
When it comes to choosing a look and feel for your product an extremely valuable tool that I use on a daily basis is Dribbble. Dribbble is a community for high quality designers who share their work and get feedback from the community. Part of being a product manager is being efficient and not re-creating the wheel so I often use Dribbble to help inspire my design, color palette and UX choices. If you are building an app, website, packaging or branding, Dribbble is a great resource that more product managers and designers should leverage in their daily workflows.