1. It is hard to get the EQ (emotional intelligence) right in email. The biggest drawback and danger with email is that the tone and context are easy to misread. In a live conversation, how one says something, with modulations and intonations, is as important as what they are saying. With email it is hard to get the feelings behind the words.
2. Email and text often promote reactive responses, as opposed to progress and action to move forward. Going back to the zero latency expectation in digital communications, it is hard for people to pause and think about what they should say. One of my colleagues suggests not reacting to any incendiary message until you have at least had a night to sleep on it, and always trying to take the higher ground over email. While by definition reactive responses occur in live discourse, they are usually more productive. The irony is that while email, as an asynchronous channel, has the potential to be more thoughtful, it often promotes the opposite tendency to be immediately reactive. Why? Because the bark is almost always bigger than the bite behind remote digital shields.
3. Email prolongs debate. Because of the two reasons above, I have seen too many debates continue well beyond the point of usefulness. Worse, I have experienced situations which start relatively benignly over email, only to escalate because intentions and interests are easily misunderstood online. When I ask people if they have called or asked to meet the counterpart to try and reach a resolution, there is usually a pause, then a sad answer of "no."
....As digital communication accelerates the pace at which people form and broaden relationships, it is also decreasing the rate at which people are willing to resolve issues professionally and directly in-person. The next time you experience an issue over email, ask yourself if it is something that would be better served by a real conversation. Then have the courage to stop emailing and pick up the phone. Or even better: have a meeting.