I think that what was simple back when the original *NIX tools were developed is quite different than what is simple today. With more memory / CPU / advanced tools / (hu)man power, things that might have been moderately complex might fit into the "simple" category today.
do one thing and do it well
"one thing" is quite subjective. It almost never means a literal "one thing". It's possible to argue that almost every piece of software does "one thing", depending on how you set up your argument. Likewise, its possible to argue that almost no piece of real software does "one thing".