Yeah this is true, I heard they had increased their trade in values, which is remarkable because its always been quite poor. But thinking about it, it does make perfect logical sense, Electronic Arts are now refusing to do business with them, so I should think the value of Fifa, Tiger Woods, Mass Effect, NFS etc would be slightly higher then others.
Considering I only own a 360, and most of my games are yearly releases, they are probably of little value anyway, but yeah I see your point, I bet they would be worth slightly more, especially the EA titles.