So,

What's the point of blogging if email will suffice for communication?

I suppose what a blog offers is a mirror. A mirror that remembers the way you wrote 3 years back. That can tell you what you thought you thought and/or wanted others to think you thought.

So it really depends on how honest you are with yourself and/or how much you remember about your particular situation at the time.

But that's over-analysing.

What's important is knowing what's important. And remembering what's important. Which is perhaps what blogs are best for. They can help you remember.

Emails are sent. They are received and kept, or not. That is not the important part. By their very nature, emails have a directionality - outward - and that makes it counter-intuitive to expect a full record of what has been sent. Although there is, indeed a 'Sent' folder, the very fact that not many people regularly check or review it underlines the counter-intuitiveness emails reflecting information to its sender.It is rather in the reply that the sender looks for information.

Thus we come to the point of the matter. That blogs are useful in preserving a record of its writer's output for himself/herself. The directionality in a blog is always toward the user. The user, as the case may be, (and in fact, may even be the most often) the writer.

The case for a blog must, therefore, stand.