Welcome aboard.

60's-80's did produce some great films, some of my favourites were made during this period.

The late 60's heralded a switch to much more gritty and realistic horror films, many of which remain quite effective to this day. Not to say there wasn't a lot of junk made during this period as well - but as time goes on the junk tends to be forgotten and we get a "distilled" view of a time period, where it is often judged mainly on the good films that emerged.

This will probably happen with the last decade or so's films too, given time.