Really? If anything, I feel the opposite, they've ditched the moon physics from Pacific Rift and grounded the cars even more. In a sense, they've lost the detailed physics from the previous game, but at the same time they've removed some of the inherent annoying traits from the other two games (that is, colliding with some small geometry will fuck up your driving completely).
Haha, I wondered what it was that made it feel so different to the previous games; and so much less frustrating!
When I crash now, it's usually because I've understeered and gone off a cliff, or smashed into a wall - not because my off-road tyre has clipped a pebble and launched me into orbit.
Even after playing Split Second, the sort of ridiculous stuff in this game gets me. Plus, even during a race where nothing mental happens, in true Motorstorm fashion, seeing other drivers wipe out is always a thrill.
Edit: Also, I went to an event where they showcased Apocalypse in London about a week before the demo came out. They had it set up on a cinema screen and were running a time-trial competition for people to win limited editions and stuff early. It was pretty outstanding! But one thing they did mention was that the story was something fans of the series had apparently requested. They wanted to have some fun with it, while not putting too much emphasis on it; after all, it's a racing game.
Essentially, the story is there if you want it. If you think it's rubbish/pointless, you can just skip it.