I chuckled when JMS introduced that.
He got it from his Screenwriting 101 textbook: the first thing you do in building any character is ask yourself what the character wants.
For me, the interesting question is not "What Do You Want?", but "Who Are You?"
"Who Are You" isn't very interesting unless the character wants something. Simply exploring a character can be a lot of fun - Dexter
is a great example of that - but in that case, you better have one hell of an actor to back up your writing and keep the audience's attention riveted even during the "boring" navel gazing parts.
And you still need some sort of internal conflict for the character to explore, to give the question some dramatic interest. Resolving the conflict is what the character wants, so "Who Are You" and "What Do You Want?" are the same question anyway.
Dark Gilligan wrote:
They're not making the show for the damn executives, they're making it for the FANS!
Come on, you know that's not remotely true. Television is a business. Shows aren't made for fans, they're made for advertising revenue.
They're made to attract the specific eyeballs the advertisers want - just to be totally precise.