I love the way God meets us where we're at. We speak to him in ways we understand, even though it is not 'his' language. It is the language created and learned within our respective cultures. Yet he uses this language with us and allows us to communicate with him through it. He accepts altars and sacrifices and later he will use this language to communicate to us a New Language.
Yet he declares he does not need our sacrifices. They do not feed him. Still, he uses this language like an artist in order to paint a divine picture for us. The language of sacrifice will be used to speak to us of the Christ and to explain the meaning of his life and death.
i don't think sacrifices were ever needed. i tend to think they were our creation rather than God's. In fact, in one place God declares he would rather us practice mercy than make sacrifice. Yet, he adopts our language and uses it to give us direction:
He speaks our language, so that we can learn to speak His.