See, while I strongly don't like the call of duty games, and personally believe they've been over-rated, I believe he has a very healthy view of game engines here.
I mean, every-time a game engine is updated there are always complaints about the old things that were thrown out in favour of shiny new graphics. Check out Saints Row 3 for example, especially when compared to Saints Row 2. The third was far shinier, but at the downside of a quarter of the weapons, half the activities, and a far smaller city/story. Not only that, but the supposed 40 weeks of DLC that SR3 was meant to have has been buggered up, because of memory issues preventing new shiny weapons from being added unless they were already on the disk.