I'd agree that the FBI using legal means to get their hands on data isn't proof the FBI has done something wrong, but I would worry that if the FBI came to rely on it, they might be motivated to further impede better privacy protections.
Perhaps not, but the FBI using one method to get their hands on data without a warrant, while a different method to acquire that same data would require a warrant, is definitely a sign that something is going wrong.
It would be very useful to the FBI to identify whether they're looking at a solo criminal enterprise or a multi-state organization.
I'll gripe about intel community abuses as much as anyone else, but it's a lack of imagination to say there are no valid, privacy-preserving uses for this.
Historically, Google rightly identified PII as the goose that lays golden eggs, and so voluntarily put safeguards in place around it to prevent individual abuses from killing it.
The FBI could do the same. I doubt it'd be effective, given political pressure from threats and constantly changing leadership, but it's technically possible.
Do the police need a search warrant to lookup who owns a property, or leverage the white pages?