If you haven’t seen them, I recommend the Clojure guys’ talks about the subject of simplicity. They reached into the etymological history of the word “simple” to pull out its early definition, which is quite precise and IMO tremendously useful in this context, unlike the confused muddle of modern definitions.

Rich Hickey, “Simple Made Easy”: http://www.infoq.com/presentations/Simple-Made-Easy

Stu Halloway, “Simplicity Ain’t Easy”: https://www.youtube.com/watch?v=cidchWg74Y4