If you simply don't over- or undercook you food, and you do your best to keep things from catching on fire, you can make some perfectly acceptable grilled food (it is really amazing how far char, salt, and pepper can go).
But, acceptable is just that; we want amazing food on the grill. And that, my friends, means embracing the world of dry and wet rubs.
"A rub is simply a combination of seasonings that are, literally, rubbed into meat (or vegetables) before grilling. There are dry rubs, there are wet rubs, and they both have a unique calling. Know your ingredients; know your grill; then think about rubs."