Yes good code can be commended, but initially it was his small project he worked up to be his golden ticket, never expecting it to be such a huge success. I'd say he did enough good to get it shipped, in the end that is the metric. But in terms of maintenance and clean code, I am a big proponent of it and good architecture. I can't say that this makes a project successful or not but it does make it easier to deal with after it is successful and sometimes largely determines how far it can go. There is always a battle between shipping and quality and here Notch was just shipping, in terms of the end product he is a good coder and a product shipper.