Mostly it's a sign of their popularity with consumers who like being able to snap on different colors and styles that fit precisely, so seeing some of those styles show up for Surface has been a sign of its success.
But if you want to get a different look, Toast has a very nice option: real wood veneer in a choice of different woods, that's cut precisely to fit the lines of a Surface Book.
All that precision cutting makes it a little fiddly to apply, because you need to line everything up equally precisely, while not getting the very strong glue stuck to your fingers.
If you do want to remove it, you have to warm the wood with a hairdryer and peel; there's a pattern of small dots cut out of the backing that interrupt the adhesive surface you apply to the Surface that make it a little easier to take off than if it was a full adhesive sheet.
It's not cheap -- $69 to $139 depending on how many of the surfaces of your Surface you want to cover -- but it should be hard wearing, and it will stop the metal of your Surface Book picking up scuff marks.
Toast also has covers for the Surface Pro 4 $49 to cover the back and for a wide range of phones and tablets, laptops and MacBooks.