Splash Damage creative director Richard Ham explained why there won't be a beta for the upcoming freerunning FPS Brink in an interview with NowGamer. Ham says that although beta testing is crucial to games development, they've been turned into nothing more than a marketing gimmick.
"They’re incredibly important, but they also need to be run correctly. Until you put a game into the hands of hundreds of players, all with their own ideas and approaches to gameplay, you can never truly know everything you need to know in order to get it “just right”.
"At the same time, with some betas being used purely as marketing tools, some players treat a beta the way they would a demo, and they expect everything to be fully working and polished."
The company's reticence in releasing a public beta is perfectly understandable given the expectations of players and the fact that most people treat betas like demos instead of products to be tested.
This doesn't mean that they aren't testing the game, of course. If you're one of the few lucky people who managed to earn an invite to the game's controlled beta, the rest of us are jealous of you.