The “point” of the book is irrelevant; chapter 21 is disconnected from the main text, set at some remove from the events in the previous chapters, and utterly banal. It’s an extended internal monologue of the most boring sort where the author states his moral.
But the best works of literature, in my opinion, transcend simple morality tales and touch something a bit more universal and hard to define in language. If your point can be summarized in a short essay, all you’ve done is illustrate an essay at length. “This novel could’ve been an email.”
What is captivating about _Clockwork_ is precisely its depiction of violence, its almost sympathetic glorification of the id. The protagonist’s unapologetic thirst for violence is what makes the novel (and movie) interesting. It’s reminding us that violence and aggression are part of the human condition, and part of the reader, too: you may recoil, but you also identify with Alex — it’s a first person account so that’s natural.
The last chapter ruins it though with petty moralizing. The voice of Alex the psychopath is far better than that of Burgess the moralist, and the novel is better for having its terminal essay removed.