Why do Republicans want Obama to submit a budget plan?

I'll put it in a way even a liberal can understand: i tell you to go bake a cake and you do. only the cake you present me with is coconut and I wanted something else and tell you to go bake me another one. You do and present it to me but I don't want chocolate but another kind and tell you to go bake me another one... GET IT? It makes little sense to keep baking cakes when the customer (or the one who already stated if he doesn't like the cake, he won't eat (VETO) it)! Speaking of the Constitution, apparently Obama thinks he can do better without it by uming Supreme Power: