Short release cycles, continuous deployment, automatic updates, and a fear of social media tattling on beta defects are causing vendors to forgo beta testing and find new ways to get useful user feedback.
Many QA engineers I've known have had a love/hate relationship with beta testing. "It's expensive to administer and doesn't give me useful information," said one. "Too many bugs slip through this so-called 'beta testing,' so I have to test the whole app in the lab anyway," said another, "but if Marketing wants it, I can't stop 'em."
On the other hand, some organizations continue to see value in beta testing: "We need to plan for three weeks of beta phase to make sure we get better coverage on use cases and environments that we can't test against ourselves."