renderings of "beautiful aliens" was taken on successfully by Frank Frazetta in many of his stories and his fantasy art. He chose to have alien "women" (cause they were indeed women) look Rubenesque in his interpretation . He also painted women of the ancient world and "Paleo" stories look the same. He adopted and overemphasized western style beauty features and had his subjects be adapted to the environments of his fantasy worlds.
The renderings that were used to set up the CGI for the movie "Avatar" took another cultural definition of beauty by having the aliens be lithe, long bodied with highly symmetrical facial features that focused primarily on the eyes as central objects of natural beauty.
Artists can trick you into using our cultures beauty norms to draft their subjcts used in their fantasy art. So they are, in effect, leading you into buying their interpretations by drafting their subjects all loadedwith western aspects of beauty built-in to their work.
Id rather see my aliens look like the bar room in Star Wars, and not try to manipulate me