Kernels do a lot now that they didn't used to. I'm not sure what marginal features you're talking about, can you share some with us? The ABI may look the same as it was in the 1990's but thing under the hood have gotten a lot smarter, and that smarts requires more code.

As for userland.. Even OpenBSD, my personal preference of operating system and one which is known for its 'lean'ness of base userland has 10x this kloc in /bin/ and /usr/bin:

  # find bin usr.bin | egrep '\.c$|\.h$' | xargs wc -l | tail -1
    689562 total

Coreutils, by comparison:

   coreutils$ find . | egrep '\.c$|\.h$' | xargs wc -l | tail -1
     91991 total

(The difference is because coreutils doesn't contain everything obsd's /bin and /usr/bin does I suppose, openssh, tmux etc)

Either way, that's not a mad amount of code imo... Which parts of this are 'MIT bloatware' ?