"There are so many great courses in the world to review, discuss and learn from. Why would one highlight a course which has significant flaws?"
Ummm, to learn from them, maybe?
True, each course is unique, and fitted for the land by an architect. But, as many, many GCA threads have pointed out, you can make a great course out of ordinary land, or an indifferent course out premier land, or butcher a course/change it dramatically from its original incarnation. All of those strike me as worthy things to discuss in a review of a golf course on a website devoted to golf course architecture.
In addition, Ran's reviews are kind of like Kremlin statements in the old Cold War days -- you have to sift through them, and read between the lines, to get at some of his criticisms. Notice the recent Royal County Down review, where he obliquely criticizes Doak's Ballyneal and C&C's Sand Hills for being "perfect," a condition not often found in nature. And many if not most of Ran's review focus intently on the relationship between what an architect is trying to do with the lay of the land of the course.