It's probably that way because no other genre demands so many lyrics. With that being said, having the main vocals be heard is the PRIMARY goal. In rock and alternative music, the vocals are like one of the other instruments in the mix. In rap, the main vocals are like the meat on a typical plate of food. It is the main dish that dictates what the sides should be. Rock and alternative vocals are like having all vegetables for dinner. The main idea in putting together a plate of vegetables for dinner is making sure the foods are of different color. This makes the whole plate look more appetizing.
Damn...getting hungry....let me go make a sandwich.
