A friend of mine likes to say that witchcraft is just another person's religion. That is to say, if you take a central metaphor out of its context, it's going to look weird.
This framing of the metaphor implies that the lamb is just a lamb, which results in the sacrifice of the weak for the good of the strong. And, to be fair, there is a tradition within Christianity that takes this image and teaches people made weak by our society that they need to shut up and take it for the good of those on the top.
But that understanding of the metaphor is missing the central theological claim: The lamb is not worthy of praise because it is weak. The lamb is worthy of praise because it has given up all the power in the universe to come as simply one of us. And not just one of us, but the quintessential human, the human so completely human that in dying, he took on all of us that is separated from God by death and brought us back to God.
The lamb isn't suffering for suffering's sake. The lamb is God taking on the kind of body that is vulnerable, that is breakable, that is weak despite the fact that God is infinitely powerful and could have done anything. The lamb is worthy of praise because God knew that loving us in this way would result in the death of God. Yet God loves us enough to do it.
And one area of misunderstanding is that Christianity holds onto the idea of impassivity. People misunderstand impassivity as meaning that God cannot feel anything. Impassivity instead means that God cannot be caused to feel anything involuntarily. You and I can't throw rocks at God or call God names that will hurt God. Yet God chose to feel pain.
And, I think, creating the world was an act of God choosing to feel pain. Like any mother, God gave up of God's self so we could grow. God gave of God's self by limiting God's self back so God would not overwhelm us. God gave of God's self by creating something separate from God's self, something that had never before existed in reality. And when God made us, God gave of God's self by being love itself, which means crying when we cry and dancing when we dance and feeling all of the complex emotions of humanity with us in every moment.
Our existence causes God's suffering.
Yet God loves us enough to suffer for and with us.
And that's why we venerate the lamb that was slain and, more importantly, came back to show us what unification with God will look like.