Well, it's been 50 years since I read Flaubert, but I don't recall him being quite so blatant in his judgment. Emma is foolish and romantic from the start, and when her dreams are dashed she makes and carries out her choice to die. Anna is the emblem of wisdom until she makes her one mistake of falling in love and giving herself completely to that love. She tumbles from a far greater height, and though her death is mercifully brief, the horror of her fall is protracted. Tolstoy's moral lesson IMO lacks any subtlety, because Anna cannot be pitied as a fool.

Also, I may well be mistaken--I only read the book once and have not studied any commentary--but my impression was that Tolstoy could not allow Anna any breath of happiness or peace once she had chosen the sinful path. Granted, it's a Russian novel, which means suffering is the constant in every life, but he was gentler with most of the rest of his characters.