Simplification is great for language learners but an outright flaw for lossy communication. Whenever you lose some part of a sentence through interference (like a movie that decided to have a scene with people whispering at actual whispering intensity) the redundancies help in understanding the correct meaning of the sentence.

Additionally, native speakers of any language (usually) have an intrinsic understanding of more complicated grammar so there is no real advantage in simplification for them.