My favorite genre of literature is dystopian fiction, and it is from the genre I developed sincere admiration for George Orwell's 1984. In literature written today, the criteria for inclusion in the traditional English cannon includes the most well-known pieces of laic English literature that serve to ground the culture as a whole in both representation, and attraction.
A piece of literature will be acknowledged with acceptation into a literary canon. Unfortunately, it is only when a piece of work is in the canon that it is legitimately analyzed. The purpose of the "canon", however, is to group pieces of literature into areas where they can be similarly analyzed, rather than give them a kind of accreditation. It is not possible to argue about the contents of a canon, when a canon for that genre does not exist in the first place. Take for instance, J.R.R Tolkien's The Hobbit. Many people would argue it to contain literature representational of the children's genre. But many adults, including myself, consider this something to be read by all ages. Now, unless there is a canon that separates children's and adult's literature, This argument cannot take place. Furthermore, critical reading can be specified based on the canon in which the reader classifies it. The criteria for a canon is then necessary for the sake of focused analysis from different critical lenses. Whether one agrees with the type of canon literature should be in is another argument altogether. .
As with any topic in literature, there are negatives to canons. Sometimes when a piece of literature is placed in a certain cannon, there is an immediate interpretation based on the canon it is in rather than on the kind text within the literature itself. Certain cannons can create a cemented interpretations that are never argued or analyzed further. As the criteria for certain cannons tend to be based on popularity, this sidelines other works simply because they're not as popular.