This article couldn't have come at a better time for me. I'm a fourth-year University student, about to graduate with a BA in Cognitive Systems (Psychology). I'm also about to be interviewed for a job with a local game developer, and I've been struggling to figure out how to explain what it is I can offer them, skill-wise. This is it. *This* is what I am educated and prepared to do, this is what I *want* to do. Thank you, Escapist, and thank you, Spanner.
In response to Mumbles, I don't think this is the job of the core development team. They're too close to the product to see the flaws. That's why there are testers, to find the flaws in the game. It takes a third party, though, to examine and quantify how the players and the game interact, and see the problem areas overlooked by both developers and testers. After a while, players of a game get used to the quirks and questionable design elements; the key element is making sure new or inexperienced gamers aren't prevented from enjoying the game.
Conceivably developers could be doing this job, but that means they'd be spending their time watching people play the game, rather then actually working on it. They could also beta-test the game themselves, and market it, etc. Conceivably. But it would be bad.