I played this weekend in a game I am new to (2d weekend in it) and observed the opposite phenomenon. The game started as 15-30, but was bumped to 20-40 at the request of several players. I was a little uncomfortable with the stakes but didn't object (one objection would have kept it at 15-30)and played anyway. The game kept going overnight with some players leaving then coming back. I played for a long time the next day and we switched back to 15-30 around midnight. We did it because the game was dying at 20-40. An action player or two left and replacements were hard to come by. When we switched back we got a couple of more players and the pots got bigger. Players had tightened up at 20-40. The game was also more passive at 15-30, maybe because people didn't have as much a raise or fold mentality. A few of us discussed it and thought it might be a better idea to keep the game at 15-30 in the future. Granted this was in a more limited poker market than LA or Las Vegas, but Bellagio seems to get a lot more 15-30 than Mirage 20-40.