Well, it is less expensive to build data-centers and tap fiber-optic lines than to send rockets to orbit and probes to Mars... (especially the way NASA does it compared to, say, SpaceX.. but that's another discussion)

But in any case, I think it's fine to get these numbers public because it's still taxpayer money. I think it would've been worse of Snowden NOT to release numbers just because they aren't as shocking as they could've been.

Transparency should be about showing you what's there, not about cherry-picking things to form a narrative that distorts what is there.