I can speculate on the reason for the new interest of the WSJ in social class but it is meaningless. Possibly the owner of the WSJ, Rupert Murdock, continues to be offended at the miserable treatment he has always gotten at the hands of the British Upper Class. He may have told his staff to write about it.
The real story is that class, which means 'hereditary class', has been gone in the United States since 1960, but an hereditary class remains everywhere else in the world. This is the true exceptionalism of America.
I have done two things in this matter: I wrote a blog proving the elimination of America's hereditary Upper Class and showing the date, 1960, in this blog.
I wrote a blog explaining why this happened in America. The Wall Street Journal reporter on this story finds several explanations for the end of America's Upper Class. He includes changes in religion (end of mainstream Protestants which happened a decade later) and lack of upward mobility for minorities into the Upper Class. No other serious person has thought about this subject nor written about it, so the reporter was stuck with his own nonsense.
There was one reason for the end of the American Upper Class and I wrote about it here. In the American army of WWII everyone of talent could become an officer. Not true anywhere else. After the war, these skilled managers, forming a large group, took over American corporations in a 15 year period. They displaced the hereditary American Upper Class by pure numbers and talent.