Gamasutra is carrying an article today from the Independent Games Conference. In remarks during IGC, Richard Garriott discussed how having too many beta testers was a bad thing:
"We burned out some quantity of our beta-testers when the game wasn't yet fun," he said, adding, "As we've begun to sell the game, the people who hadn't participated in the beta became our fast early-adopters."
He continued, "And the people who did participate in the beta, we've had to go back to and say 'look, look, we promise: we know it wasn't fun two months ago, but we fixed all that. Really, come try it again.' We've had to go out and develop free programs to invite those people back for free before they go buy it. So the beta process, which we used to think of as a QA process, is really a marketing process."
It's an interesting read with unusual candor from Garriott.