According to director Keith Alexander, the measure is meant to improve the security of NSA data
News XKeyscore
NSA Chief Heckled At BlackHat As Agency Defends XKeyscore
Alexander fends off attacks from BlackHat audience member
NSA XKeyscore Tool ‘Could Crack VPNs And Expose The Anonymous’
A slide leaked by Snowden reads: "Show me all the VPN startups in country X, and give me the data so I can decrypt and discover the users."