I've always thought that the easier an instrument is to "play", i.e., make a sound on, the harder it is to play well. That's why a harmonica in the wrong hands can be a real pain.

I almost never like the electric piano that was so omnipresent in the 70's. An example is the one on Steveie Wonder's "You are the Sunshine of My Life" (it is playing on the muzak as I write). Even played well it sounds artificial and uninspiring, and lends itself to pointless noodling of the jazz sort.