Childrens' distaste for vegetables is both well known and a common theme in advertising and entertainment. Yet, we must acknowledge that children tend to speak the truth, unencumbered by social pressure and adult taboos.
As an adult who freely admits a limited attraction to vegetables (raw carrots, celery and fresh salads are favored) I am inclined to defend the youth of our species. While I suspect that most humans like the natural taste of meats, fish, eggs, dairy products, nuts, fruits and grains, most of us must season our vegetables, fry them in butter, caramelize them with sugar or smother them with sauce before we enjoy their flavor; even salads are made palatable by topping them with dressing, cheese and croutons. By contrast, most of us enjoy fruits and nuts right from the tree (or shrub) and require only a bit of cooking before we eagerly consume meat, fish and eggs.
While early human ancestors may have munched on leaves and other plants to supplement their diet, one suspects that vegetables, given their taste, may have eventually gained favor in areas where other nutritious foods were in short supply. Perhaps this is all my self-serving imagination, an attempt to justify my child-like approach to vegetables. Then again, when certain companies market veggie drinks to make their consumption more tolerable, there must be something to my theory.