They appeal to some folks and don't appeal at all to others. Sadly, those that like them sometimes force the others to play along.
I actually don't mind having a concise, well-written statement, but I utterly detest (with every fiber of my being) the process of developing a statement. It's hard, mind-numbing work for any group to collaborate meaningfully on this kind of creative writing assignment and the result will generally not please anyone. Most participants will really resent the process and dismiss the result.
If you're a person who like mission statements, more power to you. But don't kid yourself; 80% of the people around you will resent you and hate the process.