I'm a little torn. The potential for such a system to be abused by the Dollars-over-Quality side of the industry is really high.
But then lower price points can level the field a bit between the high-disposable-income-teenage-gamers and the strict-budget-adult-gamers. A boost to the DLC market would also help stabilize it, bring down prices, and draw out market-standard prices.
Plus there's the reality of the situation. We're already getting hit with repackaged cut content, gimped games, and continuously growing multiplayer via DLC. It's not some theoretical concept or anything. That part is already happening and it's profitable so it's not going away.
All THQ is proposing is a drop in the base-game price.