> This looks like a lot of work for what amounts to very little end-user benefit.

Oh, but how wrong you are.

At London Emacs meetup Wilfred gave a talk about his motivations for this work. One of the big and most obvious benefits is this:

while porting some feature to Rust, he discovered a bug in Emacs, fixed it and got given commit access for his work.

You can read the transcript of his presentation here:

http://www.wilfred.me.uk/blog/2017/04/30/remacs-talk-transcr...