To a layman, it seems possible that the co-pilot seeing the altitude dropping rapidly and not sure which other instruments to trust, concluded that the plane was in a nose dive. The crew of 1979's TWA 841 (the nose dive over Michigan) knew immediately that they needed to pull back. I'm not saying that these examples are too similar, but such a mistake is something I could understand to be a result of two or so minutes of profound confusion.
AF447 pitch didn't drop below the horizon the entire time. In fact, for most of the fall, the nose was pegged somewhere above +14 degrees of pitch.
As a layman I wonder what hints the center stick was giving Captain Gibson in 1979 compared to those offered by the side stick in 2009.
In 1979, you'd have control forces you could feel. In 2009, the side-stick removes all tactile feedback.
Another point worth mentioning is that during the hard pitch-up by the pilots of AF447, the stab trim wound all the way back to +13 degrees.
Interesting that many are not discussing this point.
Any A380 pilots want to comment on the display of pitch trim there? Interesting to know if they did it differently.