The jumping puzzles immediately appeal to metagaming instincts, like when the puzzle game gives you a fixed number of pieces so you know your solution will incorporate all of them. Once you realize you have found a jumping puzzle (whether one with an achievement or one that just leads to a chest), you start looking for the next perch. You stop thinking about the terrain as a game rather than a world, and you put on your designer’s hat to think of how you would design the next step.
“Hmm, there is an achievement named “Urmaug’s Secret. There is an NPC named Urmaug in Lion’s Arch. Let’s give that area a second look. Aha! Now how do I get up there…”
People in games and stories like to design games and puzzles for the heroes, and they are usually fair ones that they can solve. If I am protecting myself and my stuff, I am not playing fair with whoever is trying to kill me. Also, I am probably not going to design a home with one path through it, in which I must pass through every room in the house to reach my bedroom.