Macbooks: Case or no?

I'm headed off to school in a few weeks and have had my new macbook for about a month. Being at home, I've had no trouble keeping my new pride and joy in pristine condition, but obviously this might not be the case in a school environment where the machine is being moved constantly.

My question is: Is a case worth buying for a Macbook? Not a sleeve or anything - I've got a laptop section in my backpack - but like a full body cover, like the speck satin kinds of cases. I generally take good care of my electronics, but is a macbook something that will look pretty dinged up a few years down the line if I do not invest in protection? I don't use a case on my iPhone, because I feel that added thickness takes away from the aesthetic of the product and I replace it every 2 years anyway. I share the same philosophy with the Macbook, but obviously it's a much bigger and longer-lasting purchase.

Thanks in advance for your feedback!