Talking in person has advantages: People are more intensely aware of information they've heard in person. Taking the time to talk tells the recipient that the stuff is actually important to you; tone of voice and body language also convey this. They feel more appreciated.
Originally Posted by Suelin23
Talking in person can be more efficient. Email is not a good way to negotiate. Even using email to establish a time and place to meet has difficulties: the last person to send an email can't know that it's been received, so there's no natural moment for assuming both people have committed to a specific proposed time. Talking in person allows for instant communication and and nuances, and may result in a mutual agreement that's different from what either individual would have proposed before the discussion.
For example: In person, you ask someone to do something and they say "OK. That will take me about 2 days of work." and then you might say "Wait a minute: I didn't realize it would take that much of your time." A discussion might result in a clarification or change in the assignment.
By email, you send the assignment and the person thinks, "Should I reply that it will take me 2 days? Once I reply that, should I wait for them to confirm before I actually start? What if they don't reply back for several days? Would sending such an email make it seem as if I'm reluctant to do the work? Maybe I'd better just do it and not send an email." Much more complicated than just a quick reply within an in-person conversation.
Email also has advantages: it's a good way to convey and store complex information, and can be read quickly and forwarded to others.