If you write to make money, and people can't identify with your characters, other things being equal, you're going to sell fewer copies.
If you write to make a point, and people can't identify with your characters, other things being equal, you're going to attract fewer readers to whom you can make your point.
Why? In both cases, because people don't like reading stuff where the characters do random things for incomprehensible reasons. That's not an interesting book. You might as well write a book about squares in a video game that move according to the output of a random number generator.
That's not to say that surprising things can't happen. They have to, or again, the book isn't interesting. But the characters have to be recognizably human to us, or it quits being a book about human characters.