The movies starring Monroe, Sinatra, Elvis, Kelly, etc all still needed well-written plots, good effects, and a talented side cast in order to succeed. These days if something stars Chris Pratt or The Rock it will make money virtually no matter what. Think back to the 80s when action stars like Schwarzenegger starred in dozens of B movies with virtually no plot and garbage effects and would sell the film to audiences purely off of their starhood. You couldn’t really do that 20 years earlier.