iin to have this opinion about food?

Although on the surface it might seem like a trivial question, in reality it's a very deep and profound one. In order to understand why, we need to take a step back and look at evolution.

Food craving is an evolutionary device that makes a species eat food that provides it with the necessary nutrition. Humans aren't the only one who get food cravings. They experimented on sheep. When they lacked a certain vitamin, they were more prone to eat food that had that vitamin. I tried to look up that research now but couldn't find it.

This device is pretty weak and can be easily manipulated. Marketers and fast food chains spend a ton of money on such research. They add flavors to their food that make you crave those unhealthy food. Say some fruit or vegetable that is rich in a certain nutrient may have a particular smell or flavor. When we lack that nutrient, we crave that food. But if the same flavor is artificially added to french fries, instead of craving the naturally occurring fruit, we now crave french fries. It is easy to trick our device that was once so necessary for our survival into making us eat food that is not healthy for us.

So, I will have to agree with your father on this one. If you crave for a natural food - fruit, vegetable, meat etc that are not artificially flavored, then you might actually need nutrient that is present in those foods. But if you crave artificially flavored food, it's because your internal device has been manipulated and you don't need to eat that food.