Because the population of Cali was the most legitimately pissed off in late 2003 that they had been in a very long time, largely due to our fair state's dysfunctional politics over the past couple decades. Davis didn't cause all this himself, far from it, but he was unfortunate enough to be in office at a time when the state's population was in an extremely surly mood, and the captain goes down with the ship.

Ideologically speaking, I don't see any real difference between the two; the real difference is that Arnold's simply a much better politician than Davis was. His approach since 2005 seems to have worked pretty well. He works with the Democratic majority in the State Assembly in drafting all big pieces of legislation, then these are submitted to the public via referendum, and in doing so, they manage to cut the California Republican Party out of the loop. That approach probably wouldn't work in any other state, but it's quite effective.