Exactly as loulou57 said, extra counter space and a cover when the burners are still warm. And also agree, they limit the size of pan you can put on it.
Our Springdale and Dutchmen had the cover. The Dutchmen could not be removed, but the Springdale could be removed, which we did often.
My current Outback did not come with a cover, so we purchased a black wooden cutting board with a cork back that lays very nice over the stove. It serves for extra counter space, and an actual cutting board when we need it. Although, if the burners are still warm, we don't put it on the stove. The hot burners would probably burn the cork. But we do 99.9999% of all our cooking outside anyway, and only use the stove inside on very rainy, or very cold days. But that cutting board sure comes in handy. It also serves as a portable desk top when laying in bed watching television, for playing cards, and using for a makeshift table. Very versatile.