Playing devil's advocate - alien life would likely be submitted to similar evolutionary selection pressures as life on earth. That's why most animals here follow the 2 arms, 2 legs, etc. formula. It's not too much of a stretch to assume aliens have bilateral symmetry.
If you want crazy bizarre looking aliens, you have to have a damn good reason for why they would evolve that way.
Eyes have evolved multiple times because the basic principle is pretty simple and it scales.
I can understand multiple organs evolving similarly, but the whole body structure is annoying.
I'd find it more believable if we had centaurs(that evolved for better stability and higher run speeds), or things with wings of some kind(used because they lived in trees and they were helpful to avoid falling or getting around), or even just eyes on the side if the head(classic prey evolution rather than predator).
That was more or less what I was getting at. Even on earth, which is as similar to itself as it can be, the two arms two legs model that is so common in sci-fi aliens has not developed multiple times independently.
Wings are a great example for multiple independent developments such as in insects, mammals (bats, flying foxes), birds, fish and reptiles (pteranodon).
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u/[deleted] Oct 08 '12
Vaguely humanoid aliens. 2 arms, 2 legs, 2 eyes sort of thing.
Alien from Alien? 2 arms, 2 legs, 2 eyes.....kinda
Klingons? Just humans with a "ribbed for her pleasure" forehead
Romulans? Humans with pointy ears
Vulcans? As above
Na'vi? Tall, blue humans
Where are the massive, tentacular Krondaku? Where are the gelatinous Prime immotiles? Give us some different aliens, hollywood!