Beatty says that the beauty of fire is that it destroys responsibility and consequences. If something causes divisiveness, it should be burned, destroyed. If something causes disagreement, it should be destroyed. If there is any literature, work of art, or type of entertainment that provokes people (or even a single person) to question the ways a society behaves and conditions itself, that should be destroyed. If you burn a problem, you don't have to give it a second thought.
Beatty is enforcing the idea that if we eliminate all types of controversial material and any kind of influence that encourages individual thinking, people will gladly give up their individuality. And with that, they give up responsibility for thinking as individuals; and therefore they give up responsibility for themselves. In doing so, they become puppets of the governing body. Since they are no longer responsible for themselves, they fear no consequences for their actions. In short, Beatty is explaining the idea behind the phrase "ignorance is bliss." If people are kept in a state of ignorance, they won't be interested in thinking critically. They won't be interested in controversy or responsibility. They will be happy (bliss) in this state of thoughtlessness (ignorance) because they will not have to think for themselves. They will not have to consider difficult issues because all of these ideas will have been burnt.
In the book, fire is a means of destroying all original, controversial, inspiring, or challenging ideas. Fire maintains ignorance. Fire is therefore symbolic of anything that destroys ideas that challenge the status quo. In many respects, fire is symbolic of censorship. Some governments and institutions censor things that they feel are inappropriate or that are contrary to the social values they ascribe to. In terms of human nature, fire is symbolic of humanity's (or a person's) willingness to destroy or suppress controversy and radical ideas. That willingness to destroy is caused by fear and an attitude against change and progress. If we don't face difficult challenges and issues, in personal and social situations, we essentially burn them. In "burning," we intend to ignore and forget them, choosing the comfort of our blissful ignorance. To burn something is symbolic of ignoring a problem.