Well, geez, Doc. A book about the King's stilts called The King's Stilts?Couldn't you have made this one a bit more interesting?
Okay, okay, we can give the guy some points for practicality. The title at the very least introduces the reader to the two main elements of the story (a king and his stilts). Plus, it fits neatly on the spine of a hardcover book. Bingo.
The question is, then, why is this title the one that most fittingly sums up the story? Why isn't it The King Works Really Hard or Lord Droon the Sneaky? Why isn't it Binn Needs Cats or Nizzards are Bad?
The answer is that the story—though it is about the overall kingdom and its safety and upkeep—really focuses in on the king and how he balances his life and role as a leader (not to mention how he balances on those red stilts of his).
The story couldn't simply be called The King because the King just wouldn't be the King without those stilts (as the story proves). He's defined by what he does for fun, not what he does to pay the bills (does a king have bills?). Also, it's not about Elvis, so there you have it.
That concept of not defining yourself by your job or becoming too overworked and overwhelmed is an important thread that runs through the story. By introducing the reader to what the king likes to do in his downtime (when he's not busy being king), we get a sense of these two sides—the royal leader and the lover of stilts. And those two sides are most definitely not mutually exclusive. In fact, they're mutually beneficial.