Simplicity pretty much excludes generality in a lot of cases, you're only able to port code to the GPU if it wasn't a million LOC to begin with, so you're pretty much making the case for it.

Note that Simple != Easy or Naive

Hardcoded structures is potentially exactly the kind of simplicity needed.

What's not simple is a general "this solves everything and beyond" code-base with every imaginable feature and legacy capability.