Since we are discussing character creation and worldbuilding, I will express one of the reasons my players and I have enjoyed Fate: character creation often explicitly builds the setting with player-made character/plot/setting hooks.
When I say that "character creation builds the setting," I do not mean simply any implicit setting that results from the player choosing preexisting class, race, and background options. Instead, I mean that the players often can create setting or have ways to connect themselves explicitly into the world via their aspects. For example, a player could create the Trouble, "I won't let Baron Ziegermann foil me again!" This Trouble tells me that a "Baron Ziegermann" exists in the setting. It tells me that the PC has experienced difficulties with Baron Ziegermann in their past. And by having this as a trouble, it tells me that the player wants their character to encounter Baron Ziegermann in the story.
Alternatively, a player could create for their character the high concept "Disgraced Ex-Bodyguard of Prince Alfric." This gives me, the GM so much information about the world and the stories that the players want to experience. Here in the latter example, I would have presumably worked with the player in developing this aspect:
* Player: I want to play a disgraced bodyguard for a noble.
* Me: Okay cool, but let's flesh that out more. What noble position did they hold?
* Player: Maybe a prince.
* Me: Sure, that works. I have a few more questions. 1) What is their name? 2) How did you fall from grace as a bodyguard? And 3) Is the prince still alive or did you fail to protect them?
* Player: How about 'Alfric'? Hmmmm... how I fell from grace? I failed to protect Prince Alfric from being poisoned because I was "distracted" from my duties by a romantic fling with one of my fellow knights. How about "yes" the prince is still alive, but maybe the prince is now permanently crippled?
Though the latter two questions are not explicitly part of the High Concept, they are questions that would likely need to be answered for the understanding of the high concept. This High Concept (and associated questions) gives me, the GM, "meatier" setting material than if I had created this NPC as part of some nebulous worldbuilding prep. How is this "meatier"? I did not have to pre-create this NPC and dangle them like shiny objects in front of the players. Instead, the creation of this High Concept entails and conveys player investment into the creation of the setting, the story expectations, and obviously the character. The aspect represents potential plot hooks that the player is offering the GM as part of the rules mechanics.
This is not to disparage worldbuilding as a GM exercise, but I have found that the collective group often gets more out of a setting when they themselves contribute to its shape and contours through their characters. I also want to be clear here that players contributing to setting creation is definitely possible in other games. From what I have read, and perhaps [MENTION=16814]Ovinomancer[/MENTION] can chime in here with his experience, but Blades in the Dark has a similar goal, but comes at it from a different tact. As part of character creation, the player selects a few listed NPCs who act as either allies and/or rivals. This is meant to help the GM generate character-tied NPCs in advance. IME, however, Fate empowers that process more consistently than I have experienced with D&D.