Sorry for the late reply, but I'd say if you can attach a keyboard and do more of the tasks that a traditional laptop does, it can replace the traditional laptop. Then you have one device where you can pop off the keyboard when you are on the couch, and pop it back on when you are at a desk or need to do some typing.

Not my taste, I still prefer the traditional laptop form-factor, but Apple is actively pushing their (expensive) keyboards so its worth asking why not allow compiling of code.