Companies have to speak a common language with the regulators who test the product, they can't simply write "hand-rolled flaxen seed with almond dough" so they write up the common chemical ingredients found via testing.

E numbers are assigned to common additives (e.g. E1105 is an egg white enzyme used as a preservative, E1400 (Dextrin) is a starch thickener abundant in corn)) to allow for a standardized vocabulary so that the regulators can actually test for safe levels of these common additives.