My family and I have been big Apple fans for years, and we love our MacBooks. As well as using them at home, I've also used Macs in the workplace when teaching my digital media creation course: essentially how to do photo, audio, and movie editing.
In my experience, cases offer a great way to protect the machine, as well as giving opportunities to customize and give it a different look, or feel. A good case will guard the Mac from potential damage and blemishes, such as knocks, scratches, dirt, and fingerprints.