Everyone hates on email. Facebook is trying to kill email by making Facebook chat - a social stream - the primary form of digital communication across all computing devices. They're trying to "reduce complexity" by removing the "clutter". Facebook is adapting the key tenet of its flagship product - the NewsFeed stream - to other communication channels.
I'm going to defend email. Facebook's social stream in no way reflects human thinking and processes, especially when people are collaborating across multiple projects. Facbeook-style streams are useful for fast and immediate communication, but they're terrible at organizing and managing complex information. The more complex and varied the nature of the information, the less effective Facebook is at managing it.
Google's Matias Duarte, Director of User Experience for Android, has recently outlined a company-wide effort to present data to users in cards (Google Now and Google Glass already implement cards). Per Duarte, cards "make very clear the atomic unity of things; they're still flexible while creating a kind of regularity." He is absolutely correct. The human brain perceives and organizes information into "units." Some units are big, others are small. They are all atomic - singular and immediately understandable - in nature:
Yuo cna reed tihs becaseu the rbain recognizes langaueg in antomci "wdor" untis
Conversations that include thousands of words are remembered as a single conversational unit
Emails are organized into threads by subject
Email more accurately models how people think about and manage the disparate information in their lives, if used correctly (please don't respond to my "thank you" email with a totally random request). In our digital age of hyper-everything, email overflow is a real problem, but the basic structure of email as a way to organize and think about information is sound. I'm not suggesting that email is perfect. It's not. Email has many problems, but it's far better than social streams that don't model how humans manage and think about different pieces of information.
Most of email's problems are not inherent to the medium itself, but how it's used. Perhaps the biggest problem with email is that it's abused for every kind of communication - office jokes, to-do lists, email blasts, information feeds, project updates, calendar invites, and more. There are specific applications designed to accommodate each of these scenarios, but most people don't know or don't care to use different applications for different in different contexts. Unfortunately, everyone just falls back on email because it's simple, free, and they already know how to use it.
Perhaps the ideal email client of the future is the one that recognizes all of these distinct use cases, and automatically sorts email accordingly.