I think possibly the suckless people think what made early unix and Plan 9 great was the minimalism compared to today, but I actually think it was the consistency: The OS was written and documented by one vendor and not loosely cobbled together like modern Linux distribution. This means that it is very easy to find your way around it once you've familiarised yourself with it.
In that regard, Emacs fits the bill (if you only live inside it).