Barry makes a lot of money at his room while the tournament is going on, as he gets special permission from the city to keep it open 24 hrs. a day for the whole week.
There are some people that aren't from there that you'll see at his pool room that week that you won't see at the tournament venue. hardly all week. There is simply a lot going on at the room even when the tournament is still in progress each day. It's nice to have a choice as to where you want to be at the moment, the tournament or the room.
Not to mention as others have said, how would you have enough seating if you had it in the room. Plus if players are matching up all of a sudden you'd have to tell them, wait we have to clean up now for the tournament to start you have to quit now. You would just be opening a whole new can of worms for people to complain about.