I have no idea what your criteria are for "occur naturally within the world" vs "contrived . . for no good reason".It's the difference between situations which occur naturally within the world, and situations which are contrived against the PCs because they are PCs.
By and large, with caveats for certain specific games and genres, the PCs aren't important within the game world. There's no real in-game difference between a PC wizard and an NPC wizard, for example. That being the case, it's contrived if the PC wizard is constantly on the receiving end of personally-compelling situations for no good reason. It's just bad GMing. It's meta-gaming, by treating this one character different than another character, merely because it's a PC. (If someone is kidnapping the mother of every wizard, then that's a different story.)
Given that the world is authored, hence - in that sense at least - a contrivance, and that what is "natural" within it is a function of that authorship, I am having trouble drawing any distinction. Unless you mean inconsistent, or at odds with verisimilitude.
In my personal experience, though, most players find it to be good GMing rather than bad GMing for interesting things to occur to, or in the vicinity of, or be stumbled upon by, their PCs.
Until you tell me what meaningful means here, I can't evaluate this claim.If the world is set up in a certain way, such that interesting situations are naturally likely to happen due to how things are interconnected, then that's one thing. Worlds should be built in order to encourage interesting situations. It's only when the GM starts targeting that stuff at PCs where you've crossed the line. Anything that happens to a PC because it's a PC is meaningless.
A player writes into his/her PC's backstory some details about family. The GM decides that, when the PC is captured by goblins, a family member will be in the goblin cages also. This is a deliberate choice by the GM, designed to push the player and elicit some sort of ingame response, drawing upon elements of the fiction (ie family) that the player him-/herself chose to make salient.
How is this meaningless? What choices is it negating? Why would the game be any better if the NPC in the goblin prison was one that no PC (and hence no player) had any reason to care about?
I don't know what you mean by "plot hook" - unless you mean adventure-path play where the GM tells the players what the adventure is (eg who the enemy is, what their PC motivations are, etc). I don't know how you think that relates to scene-framing techniques, or to player-driven games.In common parlance, the "path of least resistance" would be "grabbing the plot hook". The rough opposite of that is "taking initiative as a player".
As a player, there's no point in doing anything clever, if bypassing one obstacle means you are faced with another obstacle that you wouldn't have faced if you hadn't been clever in the first place.
I don't understand what you think the point of playing is. But if the PCs have no motivation to adventure, because there is nothing that they want that they don't already have or can trivially get, then the campaign is over.By talking about "cleverness" and "obstacles" you seem to be framing the goals of play in operational or puzzle-solving terms. That's not the general focus of my campaigns.
But even in an operationally-focused game (say, a classic Gygaxian dungeon-crawling game) looting room 1 last week doesn't become pointless because there are still traps and monsters in room 2. And this is so even if, had you failed at room 1, you would never have come to room 2 (eg because your PC is dead; or you're still trying to break into room 1).
Likewise, if the PCs kill Torog then they face the challenge of dealing with the consequences of unleashing things which hitherto were imprisoned. That is a challenge that wouldn't have arisen had they not killed Torog. How does that make killing Torog pointless?