Literature deserves its prestige for one reason above all others - because it's a tool to help us live and die with a little bit more wisdom, goodness, and sanity.
The greatness of literature cannot be determined solely by literary standards though we must remember that whether it is literature or not can be determined only by literary standards.
There is something frightful in being required to enjoy and appreciate all masterpieces; to read with equal relish Milton, and Dante, and Calderon, and Goethe, and Homer, and Scott, and Voltaire, and Wordsworth, and Cervantes, and Molière, and Swift.