Why do some publication venues add the degree type next to the author name? I've noticed that some publication venues add the degree type links to the author name, like MS, PhD, MBA or  MD. What's the point? (example)
It depends completely on the journal's editorial criteria.  Some journals will expect that the degrees are included (see JAMA) and some will not (see Research in the Teaching of English).  Professional ego will not come into it -- the journal will want to maintain uniformity from article to article.

Academic cultures differ as to whether degrees are typically appended to names.  In the academic culture in which I spent 30 years of my professional life, use of the "Ph.D." was seen as unnecessary -- if one identified oneself as "Associate Professor of English" or "Professor of English," the Ph.D. was assumed.