Sure there is. If they didn't respect rights then they wouldn't be going through open court, they'd be using a dark court as is done w/ FISA. Or they would be requesting all records, not merely IP records for a very narrow 35-minute window.
Our rights aren't unlimited; they can be overridden by a court when compelling evidence is presented. As far as I have read, the FBI keeps referring to the deceased as a "child porn suspect" but never reported finding any evidence of that after the raid. For all we know, this was a situation similar to SWATing and they've got supporting evidence justifying why they think one of the people reading that article may be implicated. That's only one of many hypotheticals I can think up for why the FBI needs that info. All we've heard is the facts USA Today has chosen to share, even as they admit they don't know why the FBI wants the info.. and that's kind of the point: the FBI only has to divulge the specifics to the court, they're under no obligation to divulge investigation details to, nor convince USA Today of, the validity.
Get hold of portable property. -- Charles Dickens, "Great Expectations"