Events like hover (or swipe, or trying to scroll out of the box) are really good for the experience side of design. It's that leap of faith that works that sometimes creates such a special connection between the user and the interface. If one ignores usability to favor experience then it's inefficient and poor design but I believe sometimes there's a good compromise between both.

It's also important to note that discoverability is really different than it used to be due to touchscreens and that plays a major role in usability.