I'm honestly not a huge fan of jumping puzzles but I however know some friends who really love to do them. I also think they add a nice way of rewarding people who enjoying exploring. I think they also add to the number of things you can do in game to pass your time.
The following descriptions was taken from the Guildwars 2 wiki. http://wiki.guildwars2.com/wiki/Jumping_puzzle
Jumping puzzles are open world mini-dungeons with platforming elements that require the player to find the correct route to the end of the puzzle. The reward for solving the puzzle resets daily (per character) and is typically a Grand Chest, Splendid Chest, or Magnificent Chest. Completing a jumping puzzle will also reward the player with an achievement. Some common themes for the puzzles are environments matching the theme of the zone, veteran enemies guarding the end chest, other hidden chests, and false endings.
Here is a list of jumping puzzles inside Guildwars 2 incase you never played the game.
http://dulfy.net/2012/09/16/gw2-jumping-puzzles-guides-guild-wars-2/
And here is an example of somebody who loves doing a jumping puzzle and somebody who hates them trying to complete one. This is a low level jumping puzzle and pretty easy.
https://www.youtube.com/watch?t=134&v=P2HEHxC7PZc
This is a video of a harder/higher level puzzle.
https://www.youtube.com/watch?t=107&v=5DYmfiRQJQY
I honestly wouldn't care if their was a reward, achievement, or just some cool mobs to fight. I just believe it would be a fun way to do something different for those of us who enjoying exploring.
Personally, I'm not a fan of the "jumping puzzle" thing and prefer them not to be in.
If the jumping puzzle mechanic were to exist, I'd prefer it to be very limited and exist for a more tangible reason other than achievement points.
Example of a more tangible use for something like this:
* There's a raid with a sealed off door.
* Door requires a member (or small number of members) of the raid to scale/cross some crazy jumping puzzle to release the lock (or summon people onto the other side).
* This solves the itch for players may enjoy this sort of thing and get better with practice at it. For obvious reasons these people would be in demand and likely land spots more easily in raids if they show their effectiveness at the puzzle. They get to enjoy what they enjoy, there's no achievement point attached, others don't feel compelled to do it who don't enjoy it since a raid is still needed to complete the dungeon, and there's more of a reason for it to exist.
Only an example off top of my head, but the scattered GW2 jumping puzzle and achievement model is not something I want to see (although I'm a fan of an AA system through normal playing such as what existed in EQ1).
I really like these ideas!
Example of a more tangible use for something like this:
* There's a raid with a sealed off door.
* Door requires a member (or small number of members) of the raid to scale/cross some crazy jumping puzzle to release the lock (or summon people onto the other side).
* This solves the itch for players may enjoy this sort of thing and get better with practice at it. For obvious reasons these people would be in demand and likely land spots more easily in raids if they show their effectiveness at the puzzle. They get to enjoy what they enjoy, there's no achievement point attached, others don't feel compelled to do it who don't enjoy it since a raid is still needed to complete the dungeon, and there's more of a reason for it to exist.
Like I mentioned above I'm not a huge fan of jumping puzzles but I think they can add some nice flavor to a game and add to it's potential to be a great game.