The clothes worn by pool players has zero to do with why it is not popular in the masses. Anyone saying that is grasping at straws.
Poker is one of the most popular games out there & the majority are not dressed "professionally" yet it has not hurt the popularity of the game.
Poker is a game. no different than chess.
If pool is to make it's case as a sport, and climb the ladder of notoriety, then he has a point about the dress code for professionals.
Rules have been established between leagues and unions such as NBA and NFL where players must wear suits and or dress for success while traveling to and from the game. Of course that has nothing to do with the sport or the overwhelming mass appeal-but it does carry that image of success. And that's the solid base where a house can be built.
"In order to be successful, one must project and image of success at all times"
-Buddy King "American beauty" 1999