@Tobias
You have been given many definitions of rewarding. Then please feel free to give us your definition of rewarding since it seems like none of all the things written here satisfies you.
Errant was pretty accurate with his definition of reward vs difficulty.
I’m completely satisfied with my “reward” for content being the experience of doing it. I’m old enough that I used to play games with a “high score” tracker on them or a scoreboard you could put initials into. I never got onto them, as usually it was hard enough to get to the finish line.
But games like the first Super Mario Brothers, Legend of Zelda, Final Fantasy . . . there wasn’t any reward for them. There wasn’t even an Achievement list to check off. There was beating it. The first game I legitimately finished on my own with no help (guidebooks or other people pointing out solutions) was King’s Quest VI.
And that pretty much is why I play games: to play them. Shiny wonderful items? Achievements? That’s secondary to the experience. In MMOs, usually it’s more the experience with friends and other people which I find far more appealing than “get the shiny loot”.
. . . I am extraordinarily weird like that.
I played all these games, and while they seemed simple, they were very deep.
Mario got harder the further you went, enemies sped up, which in that game signifigantly increased difficulty, the levels were designed with tons of secrets and things to find. It had challenge, and it scaled to a high level of difficulty.
Zelda had progression, and reward, you got better weapons, and new different abilities that took you to new places, places that you thought you beat had hidden secrets, and when you beat it? they shuffled the game/levels/locations and made everything harder so you could try again and be challenged.
Final fantasty? tons of rewards and even an endgame, you could beat the game at like level 50, but there were hidden enemies with more complex skills and difficult patterns, not only that but they give you super special powered weapons like pearl sword, a huge dmg sword that also does light dmg. Not to mention a really cool story for most of them, and a deep world.
Coming from that era of games you should actually expect a fairly decent challenge, and rewards (which isnt really about gold) as you play. The least rewarding would probably be mario, where your primary reward was more lives, so you could play longer.
Heres the thing, beating GW2 isnt challenging enough to be the point of the game. Zaitan was a chump, 7/8 of the dungeons was just a matter of time until success, fractals, probably the most endgamish thing, but it could use some tweaks, some more unpredictability, more exciting reward system, and some more content that appears as you get deeper in. I would throw in some bonus challenge objectives for greater rewards.