Don't get me wrong, I've had poor roleplayers and powergamers that can produce answers to those same questions. Its not bulletproof (hrm perhaps there is something to your causation/correlation argument), but I'm just saying I've avoided more instances of bad RPing by insisting on a background.
whats wrong with ensuring that when the dm puts you in a situation, to force you to have a chitchat session with an npc you dont care to chitchat with or about a subject you dont care to chitchat about, instead of sweating over what to say, on the fear that your words will be your doom, you pull out ol' faithful and show why you are a hero in this story and not a victum? {what is wrong with being a powergamer?}
And
the inability (or lack of desire, whatever the cause) to create a background is symptomatic of a larger problem. A player with a strong concept in mind can often quickly write a response to the 20 questions. However someone playing something other than a sheet with numbers (and this is more often than not the case with rampant powergamers) are the ones that struggle the most with this concept.
Why do I have to tell the DM what I will do before I do it? and telling the dm about my char in much detail is that.
And
Why do I have to make the players tell me what they will do before they do it?
edited for clarity