Symbolism, Imagery, Allegory
Picking up from our description of the tree dream: after Daniel tells Nebuchadnezzar he's going to turn into an animal or animal-like guy unless he acknowledges God and stops being so proud, guess what? He continues to be really proud and gets turned into an animal or animal-like man. Set and spike. The text reads: "He was driven away from human society, ate grass like oxen, and his body was bathed with the dew of heaven, until his hair grew as long as eagles' feathers and his nails became like birds' claws" (Dan 4:33).
If you consider it—and as mentioned in the discussion of the tree dream—the pattern of Nebuchadnezzar's descent into madness and an animalistic way of life, before ascending back up to sanity, with something he didn't have before (namely, the awareness of God) is really a pattern found throughout the Bible. You have it in The Book of Job, where Job loses everything he has before seeing that he is "dust and ashes" while God is supreme. This leads him to regain everything he had lost and more.
It's also the long-arc story of the Bible too—whether Christian or Jewish—where humanity descends from Eden into the wilderness and needs to struggle to behave before finally getting repaired and brought back to that original state of wholeness. Nebuchadnezzar also needs to wander in the wilderness—because he thinks he's an animal—before he can go back to being a king and become a servant of God. The Matrix references this story too. The ship that Morpheus and his crew fly through the post-apocalyptic wastelands of the world is called "The Nebuchadnezzar," since it is also someone wandering through the wilderness.