I think what ryhog meant (and he/she will correct me if I've got the wrong end of the stick here) was that the opinions of people who happen to be famous are not necessarily any more informed or knowledgeable that anyone else's and shouldn't be given any additional weight just because of the person's fame.
If Lansbury were giving her thoughts on acting or musical theatre or any other topic on which she could be supposed to be an expert, then THAT opinion would carry more weight, but, again, not because of her fame, but because of her credentials.
