Multiple revelations including Snowdens reveal that the data is not uncorrelated/anonymous, if it were I'd imagine it'd be of little use for intelligence purposes. Maybe I am too dismissive/cynical but I don't put much stock in what the courts decide or why on issues like this, they're all under somebody's thumb from what I can tell. They're the same folks that brought us such hits as "corporations are people and money is speech", call me crazy but I don't think they're making their decisions based on high-minded constitutional principles