What's so great about sliced bread?

Great inventions are often called the greatest thing since sliced bread. Now sliced bread is certainly convenient. But with all due respect to Otto Frederick Rohwedder of Davenport, Iowa, who invented the loaf-at-a-time slicing machine in 1912; slicing artisan bread with a decent knife really isn’t all that difficult to do. So why sliced bread as the paragon of inventiveness. Why not the wheel, or the lever, or movable type, or penicillin? Surely there are greater inventions than bread you don’t need to use a knife to slice.