Back in the days, they used slow films, so it might not be only the fall-off imperfections ...
The book Hollywood Portraits by Roger Hicks and Christopher Nisperos is quite interesting http://www.amazon.com/Hollywood-Port.../dp/0817440208
I use slow films a lot and do it handheld, so there are times when You are shooting 1 stop from wide open or just wide open.
Don't care much if there is out of focus or any focus, as long as there is an image, a moment or just a shot
Undoubtedly the very large apertures were because of the slow mediums they used. But still, the goal was to eliminate imperfection, and today that has been turned upside down somewhat, for better or worse.
"Make good art!"
- Neil Gaiman
"...the heart and mind are the true lens of the camera".
- Yousuf Karsh
"We are what we repeatedly do. Excellence, then, is not an act, but a habit".