I regard romantic comedies as a subgenre of sci-fi, in which the world operates according to different rules than my regular human world. For me, there is no difference between Ripley from “Alien” and any Katherine Heigl character. They are equally implausible. They’re all participating in a similar level of fakey razzle-dazzle, and I enjoy every second of it.
It makes sense, then, that in the romantic-comedy world there are many specimens of women who—like Vulcans or Mothra—do not exist in real life.