Could just be a case of your tastes maturing
I don't think so.
Look at the summer of 82 :
E.T., Poltergeist, Star Trek II: The Wrath of Khan, The Thing, TRON, The Road Warrior, Conan the Barbarian, Rocky III, The Secret of NIMH, Fast Times at Ridgemont High
Summer of 84 :
Ghostbusters, Indiana Jones and the Temple of Doom, Gremlins, The Karate Kid, Once Upon a Time in America, Purple Rain, The Last Starfighter, Star Trek III: The Search for Spock, Top Secret!, Conan the Destroyer
I mean WOW, THOSE are blockbusters. There's a great variety in there, too. Nowadays it feels as if every big movie is a freaking superhero flick...
You're talking about the high end. I'm talking about the mean - the average.
DISCLAIMER: THIS IS NOT A COMPARISON OF THE QUALITY OF EACH MOVIE.
So let's talk about, say, Trading Places. Love that movie - I think it still holds up to now. However, the editing and the audio (booming) is dreadful compared to even a shitty comedy in the last five years.
I get what you're talking about, but why should I care? Plains, Trains and Automobiles is still way better than any comedy that came out this year, technical problems and all. The writing and directing has gone way down.