I think it's odd to devalue the time of someone who is helping you achieve more. That's definitely not a charitable way to treat people, nor is it the way I think about secretaries and assistants, regardless of their gender. While rank and file employees are no longer entitled to assistants, there are still thousands of people across corporate america in these roles and they are in many ways the most critical people to getting things done in many companies, and I have the utmost respect for them.
It is societies attitude toward women that is in question here. Most individual assistants were valued by those they were assisting. However many assistants would be even more valuable if they were doing something other than assisting, and so by having so many female assistants we devalued females who were able to do better work if allowed (they probably couldn't get the needed education, and glass ceilings were in play).
Of course in 1950 we didn't have computers able to do many of the things assistants did. As such we needed them to manually do various tasks that today computers do better. However the sexist making it females who are doing the job harmed the better female who could have done something better, and also the less capable males who couldn't do anything more complex anyway. (though there are a lot of jobs that those males could do that are even less complex)
