Adding oil to potatoes before baking is perfectly fine, just a personal preference. Without oil the Idaho russet skin bakes up crispy, with oil the skin will carry a lot of the flavor of the oil so some people have a preference for using olive oil or peanut oil. Melted butter sounds great, but the typical baking time and temp of 400 degrees F for an hour is too high. The smoking point for butter is typically 300°F/150°C.
One fun thing I’ve tried is to rub vegetable oil, such as corn oil, cottonseed, soy or sunflower oil and then roll the potato in dried herbs and bake off. Turns out great for a potato bar topped with dairy, roasted vegetables or protein.
