Imagine if you were designing a system to store massive amounts of intercepted email data for archival and occasional retrieval. The design would be quite different from gmail and it would require a lot less infrastructure.

I think your analysis is perhaps being biased a bit by the idea that dealing with all the email data would be massively expensive.

Also, consider that phone companies already have existing government granted monopolies, while companies like Google and Facebook are significantly more vulnerable to bad press or some kind of disruption triggered by public mistrust.

Hence one possible strategy for minimizing the impact of Snowden's revelations would be to admit to the phone aspect of the powerpoint and to drastically minimize the relationships with web companies.

Also considering the power of ad network cookies and the amount of information stored, the intelligence value of internet companies' data dwarfs the value of phone call data by several orders of magnitude.