I agree with your sentiments, but I think the ride should focus on American films, not out of patriotism, but because the theme of the park and the attraction is definitely Hollywood.
I think there might be a spot somewhere in the park to celebrate world cinema, but not in the central attraction.
Of course having said that, the iconic American cowboy represented by Clint Eastwood was originated in a series of Italian films. The lines do get blurry.
On a different note I think there is a difference between an iconic movie and an iconic scene. For example while Titanic was a huge hit at the time, it hasn't aged well and won't be the kind of movie art houses will be bringing back for it's 50th anniversary, but the image of Leo and Kate on the bow of that ship is iconic and something people will remember for a long time. So the montage has to strike that balance between great movies and great moments.
I fully agree with this, which is why I would not want GMR to attempt to include those films that are generally held by film scholars as the world's greatest. Even though I might like it more, the appeal would be much more limited, and the attraction would probably close within weeks. Disney has to walk a fine line between entertaining and educating. There are plenty of more mainstream films that are great that can be included in the attraction that will make it appealing to the American public. Plus, like you say, it's Hollywood Studios, not Independent or Foreign Studios.
Still, I think there are plenty of Hitchcock films mainstream enough to work in GMR. C'mon, Disney, buy those attraction rights!!!