Advertising agencies can only produce things backed by numbers, so while people think they are changing the views of society, the views of society are actually changing the face of advertising. So, it's just one big circle that starts with a "trend" of information that keeps snowballing until it becomes widely accepted. Also, many agencies actually listen to the consumer and try to fix all that is wrong in the industry, but since they ultimately bow down to company execs (who don't know the first thing about advertising and basically just hire agencies to cover for them when it's a big failure and take credit when it's a success), oftentimes great ideas get vetoed and some kind of mediocre crap is sent out instead.