The island is a horrifying place that capitalizes on Victorian fears about unchecked science and vivisection without regard to ethics. Through this horror, Wells manages to satirize "well-mannered" society. As grotesque as Doctor Moreau's island is, it is not so different from Victorian society. For instance, Moreau forces the Beast Folk to recite the Law reflexively, without thinking about it on a philosophical level. Victorian society, known for its strict social rules, was not so different. Both operate by trying to control "deviant" behavior rather than trying to make room for the broad spectrum of human and animal behavior.
A key example that Wells is reacting to is the case of the author Oscar Wilde. Wilde had recently been tried for "gross indecency" after details of his sexual relationship with a much younger man, Lord Alfred Douglass, became public. In England, unlike several other European countries at the time, homosexuality was a criminal act. But Wilde may never have been tried at all if Douglass's father had not tried to publicly expose Wilde and if Wilde had not sued him for defamation. Wells's novel suggests that events like Oscar Wilde's trial and imprisonment have more to do with manners than with morality. If Wilde had simply kept quiet and out of the way, Victorians would likely have left him alone. In fact, because of its public nature, Wilde's trial was a flashpoint for gossip and cruelty: in a way, the law and Victorian manners are a cover for "beastly" behavior at the expense of the people who violate norms.
Wells ultimately doesn't see England as all that different from Doctor Moreau's island. This is why Prendick struggles to rejoin society at the end of the novel, and why he prefers to study sciences that feel removed from social questions. Prendick holds out hope that humanity will one day understand more about itself; he looks at the sky and astronomical sciences as the best place to find these answers. What he gives up on is the idea of seeking truth about humanity in a social setting. It feels too dangerous to him now that he has seen what it is like to have all of his neighbors turn against him and against one another.