Even I don't have my own Facebook ID, I actually don't know how it feels. However, I think it's an obvious invasion of privacy. Reason for that; first, it roles same as text massage. It contains lots of privacy things and it might contain some bad words and phrases as we sometimes exaggerate the expressions. But, most people don't care about it, especially, between friends or somebody we feel comfort. But, it's not related to our real character or personality. Nobody tells that is our real character. However, the employees might judge those expressions are one of our real aspect. Because they can't know how deep the friendship is and they don't know what our purpose is. They just read the text and think.
Second, we could be in a danger of leaking of personal information, If we tell or submit our password and ID. As we don't use variety of ID or password, they can abuse our information on the other web-sites when they record our password and ID. They can check some of our IDs on the other web-sites easily, with only one ID and password which we already gave. Even we change the password, we cannot change all the password of vast amount of web-sites. We might be in a danger. Nobody can guarantee the safety of our information.
So, with these 2 simple reasons, we mustn't be asked the Facebook or other sites' ID and Password.