@albertdahlin is my boss so yeah, i know what he’s talking about. 
I agree with what you wrote, I use that style in my personal project and yes, the biggest drawback is elm-format.
However, the point I wanted to make was different: Elm tries to solve problems “in batches”, so that the whole picture can be addressed instead than just a specific issue.
A solution that leaves a major issue open, like the one discussed in this thread, is unlikely to be embraced by core.
Beyond that, the main issues with encoders and decoders is that you have to write them at all, and it’s entirely possible that Evan is waiting for a solution to that before officially supporting any change.