As Stephen J.A. Ward from the PBS site Mediashift puts it, ethics are not "one size fits all." If these reporters can post about their daily lives on the same time that they report on serious issues, wouldn't that be mixing personal blogging with the real news?
Live reporting events are made convenient with social media, but they also lend themselves to shoddy and inaccurate reporting, just because it's so easy to make a Twitter post. And all of the trust built up with those fun posts will come tumbling down if a journalist makes an error with the truth.