re: early spy sats
In those days, the only way to get a decent high-res photo was with film. The earliest spy sats actually ejected a film cannister for re-entry and capture by aircraft. In that context, human operators and eyes might have looked like a pretty good option.
The Lunar Orbiter camera actually took pictures on film, developed them, and then scanned the developed film into a signal to Earth. More here.
Your point on how crappy computers were compared to people (not to mention heavier and more expensive) was a good one.