I don't think officers should be required to know any more than be able to open and close the Lodge. Optimally, they should at least have a "C" certificate. Early in my masonic career, my home lodge had a WM who could do little more ritual than open and close (and he had his lapses at first), but he was a fine leader and had a very good year in the East. Being a good ritualist and a good leader are not related. I've known good leaders who were good ritualists, good leaders who were not good ritualists, bad leaders who were good ritualists, and bad leaders who were bad ritualists. I would classify being a ritualist as one of those "external qualifications" we hear about.