Obama very clearly opposed this, then got in office and supports it. The clear inference here is that he learned _something_ between then and now to lead him to believe this was saving lives or in some other way acceptable.
I get 'those who would sacrifice privacy for security deserve neither'. I have to believe that there are pros and cons both ways to this, but that the scale tip toward the pros. (For the record, I'm not an Obama supporter on just about any other issue.)