A picture is a useful abstraction of reality. It forces people to think about what they'll 'answer' before they do. Some people might draw a diagram, some might draw a story, who knows. It tells a lot about people and how they think.
For some people this may seem like a fun task and they'll get excited about it, some may not find it useful and argue about it and others (the ones you want to avoid) will frown upon it and say 'Fine. I'll do it anyway'.
Most of the people I've interviewed are well accomplished engineers, but that doesn't always mean I want to work with them.
Why do you think it is NOT useful to draw a picture?
I think it's not useful because you're not hiring me to draw pictures. I'd pass on any interview where crayon drawings of my future had any impact whatsoever on the likelihood of my hire.
It's not useful because it has nothing to do with what you're hiring them for. Frankly, if I were asked to draw a picture, I'd probably walk out. If that means you don't want to work with me, then I probably wasn't going to enjoy working with you either.
I've been hiring game programmers for a long time now. I think there are plenty of other ways to evaluate the non-tech personality/team-player side of candidates. Start with talking to them.
I ask very blunt questions in this area. Will provide examples if folks are interested.
closely followed by
"Draw a picture of your job/Facebook/the future /whatever"