This question already has an answer here:
I dislike how many current sets and mystery figures come with negative expressions such as sad, angry, and mad. Sure they have their place and purposes, but I'd prefer my son not have so many grumpy looking LEGO dudes--I liked the old "every minifig had a smiling face" styles better for that reason. Is there a cost-efficient way to get replacement minifig heads with more appropriate expressions? A way to provide feedback to the Lego group?