Really? I had heard the issue was Curiosity was to be heavier than past probes, and they weren't confident the old airbag method could handle the weight gently enough.

Additionally, the "violently tumble while marginally protected by airbags" plan isn't a viable method for eventually landing humans on Mars! One more reason to come up with a "gentler" descent :)

actually, with a human on board you have other, less complicated options. We've been using them for a while: http://en.wikipedia.org/wiki/Harrier_Jump_Jet

Airbag has other issues too, like you might not land right side up, and you have to drive off the airbags / landing platform.

IIRC, one of the engineers said that material to make airbags strong enough to handle rover of this weight does not exist.

Also, they don't really want a solution that works up to the size of this rover. They want one that works for 5x or 10x the weight of this one, that could be used for manned missions. Curiosity is meant to be a test for that as part of the mission. Similar to how Mars Pathfinder was a science mission but also a test for the Mars Exploration Rovers.