Telling this to ourselves makes us want to change something, makes us feel sad, angry. It makes us hate ourselves more. If a friend would tell all these to us, we would either be very mad at them or stop being friends with that person.
Sometimes, being our own best friends can hurt. Because we care about our friend's opinions, right? Of course, a real friend won't tell us we are ugly and stupid and so on, but then, why do we do it to ourselves? Why do we always blame ourselves, and what makes us listen to this inner voice?