Nostalgia is a wonderful thing! We tend to remember the good times and forget the bad, so we may remember all the laughter but forget the boring tedious times in our lives, giving a sense that we were always laughing and having fun.

We may also complain about the poor standard of comedy on TV, the repeats we watch all seem to be so good. But, of course, we don't repeat all the unfunny and bad shows we just repeat the good ones, giving the sense that comedy used to be better.

Do you think we lack a sense of humour today? It seems to me people like a laugh just as much as they ever did; and you only have to look at the popularity of stand-up comics, comedy films etc to see that we still want to be entertained.
It's true that we are more careful nowadays about who and what we laugh at. There have been a lot of complaints about so-called political correctness - but if you think about it, there have always been subjects which weren't considered suitable for jokes. The big difference is that today it is often considered unfair to make jokes about people based on things that they can't help - eg their race, gender, any disabilities etc - whereas very often, in the past (and in many places, even today) you just weren't allowed to joke about people or institutions who were powerful.
It can be annoying to be accused of prejudice etc because you make a casual remark - but in the end, a lot of this comes from a wish to be fair and not pick on anyone, not a loss of humour.