Although I agree, to a degree on your statement, California is not the only place with variations in nature in the U.S. New England has scenery that is something to behold, especially, but not limited too, in the Fall. Mountain areas exist all along the east coast. It really isn't until you get to Florida that everything kinda becomes flat. And so on!
The way I see it. It is known as Soarin over California in California and it is about the place and in a park called California Adventure. Either by design or lucky happening, just by dropping the California reference when it got to Florida, it then easily became a cross section of things that might be seen from many areas within the country. California has a lot of it bunched up in one place, but, spread out across the nation you will find those same scenes, sans the Golden Gate and Disneyland. If people didn't get all bent out of shape about the California connection with the film, it would have stood on it's own. If the original hadn't been named Soarin over Cali, we wouldn't even be having this discussion.
We have the same ocean on the east coast (there's only one) we just name it something different. It would be nice to see a new film, but, the content has never been the problem. It is still an awesome thing to see.