Tor's main purpose is anonymity
There is a difference between anonymity and privacy. The streets have always been public and out in public there has never been an expectation of anonymity. People can recognize you. This was extended to telephone conversations using "common carrier" laws - The content of phone calls was always private but who connected to who is an anonymity issue and that is not private according to common carrier laws.
When the NSA scandal came out I was puzzled. Mobile phones are common carrier. As such the content of calls has had the problem of being broadcast and thus not as private as many would assume* but the records of who connects to whom have always been subject to common carrier laws so it never even occurred to me they would supply any type of anonymity the same as line lines. Maybe this is because I've worked for a couple of mobile phone companies so I've paid more attention to the topic long before it broke out in the news.
* The resources needed to eavesdrop on mobile phone conversations are huge but when anything is broadcast wirelessly the presumption of privacy becomes very weak.
So far the Internet has not been declared a common carrier. This muddles the issue for email. Public forums such as this one are called public for a reason - In public there is never an expectation of privacy. There are many layers of public - Out in public, places of public business, public domain, on public property, matters of public record and so on in a bewildering assortment.