While I personally am generally fine with the smart cover, it's hard to argue against the usefulness of an integrated kickstand that can support multiple angles.
While a kickstand does have its advantages, it inevitably makes the device thicker, and probably heavier. I've always used Smart Cover / Case with my iPads since they were first introduced, and never felt I was missing out by the iPad not having a kickstand. However, I always use the iPad on my lap and never prop it up on a desk. Which shows that the iPad is optimized for tablet use, while Surface is optimized for desktop use.