Simple vs. Easy
People are often equating easiness with simplicity, but they are very different words.
Simple (vs complex) - from "sim plex", literally: one-fold (i.e. not braided)
Easy (vs hard) - from "lying at, lie near"; familiar, near to our understanding
Rich Hickey goes more into details about this in his presentation. If you haven't already, check it out (I don't agree with everything he said, but it's a good presentation, definitely worth watching).
Most often, achieving simplicity is the hardest thing to do in software development and usually it requires an enormous experience.