I disagree. Encryption, done correctly, maintains the secrecy of the message.
> Your email messages themselves may be encrypted but the addresses and other metadata -- who you converse with, when, and how often -- is completely open.
Absolutely true, but this is a secondary issue that requires a combination of technical and political solutions.
> In addition, email encryption does nothing to protect your text messages, web browsing, ftp transfers, skype calls etc.
Right. But there are other solutions to these problems.
Security requires a layered approach. There's no way to protect all communications with a single solution, given our current systems.
I would like to point out BitMessage uses streams. Streams are a collection of nodes that have a particular part of their address in common. If you have an address that is part of one of these streams, your computer will listen into that stream. So you won't download all streams keys and messages, only those that pertain to you.
Your 4096-bit-encrypted email would probably not be crackable. However, the NSA would know from the metadata that your mails were "of interest" (because they know your correspondent was someone on whom they are trying to build a case) and they can come to you and demand the key, and impose secrecy on you making it a felony if you tell anyone you had surrendered your key.
Your email messages themselves may be encrypted but the addresses and other metadata -- who you converse with, when, and how often -- is completely open. If you exchange mail with a person B, who exchanges mail with a person C, who exchanges mail with a person T that is the subject of a "terrorism" investigation, your mail will be collected and, whether encrypted or not, the fact that you are thus "implicated" will be noted. Indeed the fact that you are "hiding" your email will increase the level of interest in you.
In addition, email encryption does nothing to protect your text messages, web browsing, ftp transfers, skype calls etc.