An excellent point.
The problem with watching shows older than 5-10 years ago is exactly this. People tend to critique and expect certain things from a current mindset and worldview. It's very difficult for a lot of people to take themselves out of their current era and watch a show from decades ago keeping the production time in mind.
It invites unfair comparisons and plot, pacing, and story expectations that hinder the enjoyment of a show.
I'm not saying people should forget their opinions and viewpoints, but I think people should be a bit more open-minded before critiqueing an episode, character, or series from shows produced so long ago.
This is exactly the reason I want to slap people that complain about the miniskirts. If you can't watch it in the mindset of the production era, and therefore must complain that it doesn't meet with your definition of propriety, then don't watch it. Don't go around telling me not to watch it, I don't have that problem.