Advice to PCs
As a GM, nothing pisses me off faster than a lazy PC interrogating an NPC with the "Why" question. They've done all the leg work to find this guy, survellied his home, captured him outside the circle k, and thrown him into the back of a van to ask him...
"Why are you selling stolen jewels to North Korea?"
Maybe it's just me, and I fully accept that might be the case, but it seems like shoddy detective work to go up to a thug, slap him and say, "Why are you stealing from the poor?"
If it isn't obvious, then the DM handing you the answer is going to be anti-climactic. It's like someone solving a crossword for you.
Batman never asks "Why?" He asks Who and Where? He figures out the Why on his own time. He wants to move up the ladder to the guy behind the atrocity. The why is insignificant at the moment. The why is useless information for people unable to connect the dots on their own. The why is batman's job to uncover once he knows the who/what/where/when/how.
Why is not a primary point of information.... and is quite possibly the easiest to make up (next to when, I guess), because it matters the least. It's also the easiest one to say, "I don't know too."
"Why are these kids being sold into slavery?"
"Um... lack of sports teams?"
"Why are you spying on us?"
"Why are the orcs eating all of your crops?"
"Um... because they're orcs."
"Why is the door to the refridgerator open?"
"Um... it wasn't hugged enough as a child."
"Why are you still reading this thread?"
"Um... lack of moral fiber."
GMs, train your PCs not to ask the why question.
PCs, stop asking the why question.