Its food man. It belongs if you like it, it doesn't if you don't. I don't understand some of these arguments where "the originating culture did it this way so it belongs!" Who cares how people half way across the world make their burritos, fuck culture and tradition. Cooking is art, do what you want and make it how you like. Personally I put rice in because its an easy nutritious filler that doesnt impact taste or texture too bad and which extends the good meats and seasoning and stuff out a couple meals.