Why do we have to read Animal Farm?
George Orwell had a very specific objective in writing the book. He wanted to encapsulate the story of the USSR and its leaders in a way that would connect it to a wider audience than just those who kept up with political news in a meaningful way. By choosing animals as the characters, it was also easy for him to connect certain traits and make some animals beloved and others hated according to those characteristics.
The idea was to show the dangerous ways that an ideal, like the one espoused by Old Major and the animals originally, could be twisted and perverted to serve an evil leader's purposes. As such, it provides a powerful lesson about the Soviet Union but also about any other way that political leaders use their power to accomplish things that are not always positive and often extremely negative.
So one might argue that you "have" to read the book to remind you of those lessons and to help you understand them and connect them to similar events in the present world.
It also doesn't hurt that Orwell was a very capable writer whose prose is recognized as being extremely effective so reading it will have the added benefit of improving the writing of those who do so.