A year or two after a new, more intrusive format became ubiquitous, its performance would fall back to the old format's, and, worse, the old format would fall even further because it was too subtle. So in the long run, the money would stay the same, but the pages got uglier, formats got crazier. The game theory is clear: everyone is incentivized to upgrade to the new formats, but once there, no one is better off (neither the publishers nor advertisers), and the readers themselves are far worse off.
We're seeing this now with traffic signals: if every crosswalk in the world is replaced with this 3D version, we'll see a temporary boost in safety, but in the long run it may return to normal and in my opinion, our world will be uglier. I don't like our public spaces covered in optical illusions.
In my area I've started to see red lights that are so bright you are temporarily blinded at night if you look at them. And they've even begun attaching strobing white LED's to the center of some of them. I would guess these perform great in short-term studies. Just like flash ads with games in them.