I blame the RAM requirement...
Those PC's may have a high amount of RAM, allowing the game to run more smoothly. It's a slight possiblity.
Yes, 10,000 beta keys were released, but how many of those 10,000 beta keys will actually lead people to log into Pirates Online on their
own PC's after they use their team's PCs? I highly doubt even a half will attempt to download the game, and then 1/4 of that will be able to get on the game..
So you see, they gave out so many because they knew not everyone would/could get onto Pirates Online, and many beta keys are being lost in cyberspace.