Also, culture changes, and treatening a little kid with psychological or physical harm isn't as funny as it was back then. You had to grow up in that era to appreciate it. Despite loving and being loved by their parents, Calvin is frequently terrified of them.

I think this implies that Calvin is not as unruly as it appears, and he was raised with good values, so he still obeys his parents most of the time because he knows they want the best for him.

If we still had Calvin and Hobbes nowadays, it wouldn't be as well received if it didn't change with the times. I can't picture them going to family theraphy, for example, although I haven't read all the strips.