Download Old Tweets : Useful Or Not?

Twitter is likely to announce a new feature that will let you download your old tweets. The heavy twitter users, who've thousands of tweets may now be able to download their old tweets to their computers. Currently users can only browse their tweets.

I'm wondering whether allowing to download tweets is a useful idea or not? Of course, those who are serious twitters may get a book deal for their tweets 😉 , but majority of twitter users are casual twitters.

What are your thoughts on allowing to download tweets? 😀