Fat adds flavor to food because the fat in the food is able to dissolve and concentrate the flavor and odors of the food and those chemicals are released into the air by the heat of cooking which makes it so we can taste the food such as bacon before we actually eat it.
Unhealthy foods that are junk foods taste much better than healthy foods due to artificial ingredients added to the food to add flavor to make them more addictive.
Also chicken, hamburger, bacon etc just taste better because it's how the meat tastes when it's made naturally in the animal.
Our taste buds love that meat taste and enjoy the meat more than healthier foods.
Vegetables just don't have that great of a taste to them like meats do.
Although meat and even bacon is not unhealthy in moderation.
We humans do need some meat in our diets so it's okay to eat meat and even greasy meat in moderation.
But just don't overdo it and eat other healthy foods too.
Some unhealthy diet foods can taste bad because they don't have other unhealthy ingredients in them to make them taste better.