The problem, of course, being that Emacs has become a horrible codebase to maintain 20 years of compatibility, and rewriting is unlikely to change that.
Emacs is one of the few longstanding C codebases I know that compiles almost entirely without warnings. Which is quite an achievement and speaks somewhat to it's quality.
Emacs has some design decisions that are the result of 20 years of concessions on a ton of different platforms, and some of those are questionable anno 2017.
Emacs' actual codebase definitely isn't bad.
To clarify: I'm not saying that locally the code is bad, I'm more talking about the kind of macro issues outlined in Buttery Smooth Emacs. But it's these kind of things that will be harder to "fix" in a port.
