It is all psych. People like to go where they are known (reall or perceived). You go for the tourney. Then you return for another....another...another...try a ring game...bring your other half....tell friends (advertising)...
Now the casinos that do not offer poker and or tourneys miss out on the poker players (their friends and wives). I see it all day long...guys playing tourneys and ring games..their girlfriends, wives, and or boyfriends are playing bj/roul/slots....so while you are playing your game someone is losing $$$ at casino profit centers...poker rooms in the casinos are cheap and affordable (comps) while your wife loses her shirt at blackjack
. Also poker is a no risk game..no advantage for or against the house. You cant place an advertisement in a newspaper for $200 a day (at least not in a metro area). SO adding $200 to the pot is a cheaper means of getting butts in chairs.
SO it boils down to 'advertisment' or the most new bodies in the door at the lowest expense per head.