On my way home from work today, i was listening to the Galactic Watercooler podcast (which you should probably go check out right now). The hosts were discussing The Day The Earth Stood Still (1951, not 2008), and an interesting thought coalesced in my brain.
The basic concept of The Day the Earth Stood Still is that humanity, despite being on the verge of exploring beyond the limits of our own world, is a very warlike race. To any extraterrestrial intelligence that may be watching, this is probably a very dangerous combination. In an attempt to pacify humanity, aliens come to Earth with a warning: Humanity must abandon its warlike ways.
The reason The Day the Earth Stood Still stands up as a classic is the way in which the material was presented. This is clearly underscored by another movie that told the same basic tale some nine years later, but with much less panache.
Plan 9 From Outer Space, often referred to as the worst movie of all time, told essentially the same story as The Day the Earth Stood Still. A group of extraterrestrials are afraid that, combined with its rapid scientific advancement, humanity's destructive nature will inevitably lead to a weapon capable of annihilating the universe. They journey to Earth in an attempt to stop this from happening.
The difference, of course, is in how these two movies present this story. In The Day the Earth Stood Still, the aliens send an emissary (and his scary robot) to deliver an ulitmatum, one which falls on deaf ears. In Plan 9, the aliens opt for creating an army of zombies (they only manage to create three). The Day the Earth Stood Still was well written, well acted and well filmed. Plan 9 had plot holes that you could squeeze Jupiter through, some of the most hilariously poor acting you're ever likely to see, and was filled with so much stock footage that one begins to wonder why they even had a director.
In movies, delivery is key. Even the best concepts will fall flat if they're poorly presented.
I'll leave you with quotes from the films' protagonists:
"The universe grows smaller every day, and the threat of aggression by any group, anywhere, can no longer be tolerated. There must be security for all, or no one is secure. Now, this does not mean giving up any freedom, except the freedom to act irresponsibly. Your ancestors knew this when they made laws to govern themselves and hired policemen to enforce them. We, of the other planets, have long accepted this principle. We have an organization for the mutual protection of all planets and for the complete elimination of aggression." -- Klaatu, The Day the Earth Stood Still
"You see? You see? Your stupid minds! Stupid! Stupid!" -- Eros, Plan 9 From Outer Space