It is a great example, but one cannot beat the metaphor to death. There are also artistic conventions which develop and self-reinforce (re Manga / Anime) as well as marketing forces - re Why do all female superheroes have giant breasts?

The strength of the metaphor is not that a rational analysis of alien / monster motivations leads the average fan-boy to conclude aliens intend to copulate with abducted females, but the unconscious projection of the fan-boy onto the alien / monster, and of course who would you grab then?