It's Twitter, it IS a big deal. It is the direct link between the artist (or politician) and his public. Over one million people follow Fry's tweets daily, and a multiple of that hears about them or reads about it on other websites (in fact, several times BBC News has reported on his tweets). You can be sure that I would defend a list of a million followers tooth and nail, and not just for monetary purposes.
Some weeks ago Stephen Fry was watching some live sporting event from his sofa, wrote a tweet about it, and got a reply from the presenters ON AIR. In a program broadcast to millions.
I think your position is that you don't care about these people and their use of Twitter. Fine, but THEY care.
Besides, a tweet like this from Sarah Palin is worth more than ten press releases: http://twitter.com/SarahPalinUSA/status/6823906156
How many times did twitter itself got hacked? From DNS hack to brute force password cracked (was no failed password limitation) to phishing attack to twitter employees account getting compromised to XSS attack to every single twitter account (earlier this year).
Twitter account of famous people getting hacked is part of the experience of using twitter. If someone stops using twitter for this, I don't feel bad about it.
Its twitter, not the end of the world.