I'll grant you that any food loaded with fat is bad for you - if that is all you eat. But any food in moderation is fine - the body does need fats, after all. Pizza has lots of protein, clearly a vital nutrient (though not the best source - you'd do better eating tunafish or egg whites. Pizza also has lots of tomato sauce, which is loaded with a vital nutrient (lycopene), the absorbtion of which is actually enhanced in the presence of fat and heat (i.e. in a cooked, fat-laden, pizza).
The rest of you comment is more on target - they like to bash ANYTHING that people enjoy.