Mulvey's idea about male gaze and female being gazed at are quite interesting, and it reminds me the concept that males are to act and females are being commented upon.
But why females' bodies are being targeted in Hollywood films in 40's and 50's? I feel the main reason is the targeted audiences at that time are thought to be male-oriented. Male audiences, who go to theaters after work, even by themselves or with their partners, were looking forward to see something interesting and attractive, which cannot be seen at any other time in public. This is what Mulvey meant by Voyeurism, a psychoanalytic term that means a secret kind of looking that produces illicit pleasure and has sadistic implications. Cinema's setting allows voyeurism because the extreme darkness in the cinema and the contrast with the bright screen. Audiences, especially male audiences, feel save to look at fragmented female bodies in the cinema without being notice by other people that they are focusing on part of female bodies.
Mulvey's idea can still be used in today's cinema settings and advanced technologies. First of all, today's cinema still has the dramatic contrast between dark cinema and bright screen. The second reason is that the advanced technology, such as 3D, give more convenience to audiences to have a secret look and the view is way more vivid, direct and appealing.