First off, I'm not so sure that the author of the article is saying that the NBA is less successful or less of a sport because there has been less parity within the league. I kind of got that he was just saying that when a new season comes up, it's easier to see at the beginning of a season who will probably be winning a title in the NBA than in other sports.
I think he is also trying to say that the long term health of the sport would be better if there was greater parity, a false conclusion as far as I am concerned.
The reason is because I believe that the NBA, unlike other sports, is dominated by so few individuals and if those individuals don't have player movement, then how is parity going to be decided. In baseball the greatest pitcher in the world only goes out and plays once every five days. In football a great and dominating defensive or offensive player can take a team only so far before he has to rely on the other side of the ball for success. Peyton Manning, as dominating a QB as he has been has only seen 1 Superbowl, Marino only saw one. In hockey, even the greatest of players is still only on the ice 2/3 of the game. Goalies can dominate but they can't score.
Only in basketball where the true greats can play and impact the game on both sides of the ball can one player really elevate his team to greatness. Take a look at the LeBrons in Cleveland. Take James off the Cavs and replace him with a decent SF like Rashard Lewis or David West and they are not anything more than a 7 seed with a quick exit. If they even make the playoffs.
Parity will always be less evident in the NBA because since expanding into the markets that the league has since the 1970's, the last time parity existed in the league, one special player makes that much of a difference.
Boston: Bird, KG
LA: Magic, Shaq, Kobe
San Antonio: Duncan
Miami: Shaq
Houston: Hakeem
Chicago: MJ
Detroit: Isiah and the exception team of 2004
But if that author thinks that Mr Stern is rooting for anything but an LA/Boston Finals this year, he is only kidding himself. Basketball, when great teams oppose each other with great players on either team, might be the single most entertaining of the 4 sports. Basketball fans will tune into games where their home team isn't playing. Can the same really be said about any other sport other than football?