Adam Engst on why email rules:"It all comes down to two simple facts: email is based on open standards, and it's the lowest common denominator for Internet communication. Any communication system that wishes to supplant email will need to offer both openness and ubiquity, and nothing available today comes even close."Gina Trapani says there's a time when shutting down email makes sense:"If you're looking for a quick answer to a question, a phone call (when the person on the other end picks...