Even if one thinks that the policies of the Obama administration are basically correct and that Barack Obama is, unlike [insert name of likely future Republican president here], basically a good guy, he doesn't actually control the day to day operations of a sprawling surveillance state which includes tens of thousands of people and many private contractors. Even if abuse of power isn't state policy, it's almost unfathomable that controls exist to prevent abuse by individuals within the system. Also, too, unfathomable that we'll ever hear about such abuses if they happen. Because secret.
I get that people want to trust Obama, but he's really not in control.