As the cost of doing so diminishes, so does the requirement for justification. These days, the only noticeable cost is psychological. IMO, sufficiently justified by "we might need it one day".
Of course, 20 years ago, or even 5 years ago, that wouldn't have been true, and that's the mindset most critics are coming from. That you need a really strong reason to be doing some kind of mass data collection like this. I just don't agree with that claim. If you can do it, you'd be stupid not to.
