Watex, there HAVE been a lot of blogs hacked as you say, but they're largely Club Penguin blogs and for whatever reason the culture in CP tends to encourage people to make lots of other people admins and pass around passwords. Not to mention they tend to be younger and not know how important keeping passwords safe is.
The internet is safer than you think, and Club Penguin is less so. I wish the people in charge would change things so that people would be a lot more restrictive about passing passwords and access around. It seems endemic in the game, and it's very, very unwise. People get shut out of their own blogs all the time, because they made somebody that's untrustworthy admin.
Remember, if you give your passwords to somebody, or give them admin status, it's not really YOUR blog anymore.