Magician, I think you need to remember the knowledge and experience of some members may trump your opinion here.
At Movie World, you can get a carpark that is less than 60 metres from the front gate. At Magic Mountain, it's that distance just from the metal detector to the gate... and its a hell of a lot longer to the parking lot. Good luck getting parking anywhere near that outside of a Disney park.
The fact of the matter is that the carpark is very close to the park's eastern border. They can't build west, because of residential. They can't go north because of the creek and housing, South is studios, etc. East is the only direction they have broad control over - and if you want to build more - you need land close to the park. The parking lot is close to the park, so thats what they'll use. Of course, council will most likely impose conditions on them that if they resume x number of parking spaces, they'll need to build another x number.
So they're not getting rid of parking spaces, they're relocating them.