Yes Pizza is benificial to our diets
No, pizza has no significant benefits to our diet.
It has dough (carbohydrates), it has cheese (dairy), it can have pepperoni or other similar materials (meat) and it can have things such as pineapple or pepper (fruit and vegetables) it has all the things from the good bits of the food pyramid. So in moderation, yet again pizza is a good thing for your health.
To say otherwise is blasphemous,
Pizza contains multiple food groups, which is extremely healthy. You have meat, dairy, bread, vegetables, and oils (as well as fruit for the hawaiian pizza people). Where did the idea that pizza, hotdogs, burgers, and sandwiches are bad for you come from? These are foods that have the most variance in food groups and thus, most nutrient content.