Signs that direct messages are being overhauled have been evident for weeks. Recently, Twitter began testing a feature that allows people you are not following to send you direct messages. That feature began rolling out globally this week. As All Things D notes, direct messages were a long-neglected feature that many expected Twitter would eventually kill. But the rise of messaging apps, and Twitter's ongoing quest to attract mainstream users, have made the company reconsider their value. Twitter wants to be the hub of the global conversation, and private messages appear to be an increasingly important part of that.