I'm not a comedic genius. My track record is shoddy at best. UNLESS YOU'RE TALKING ABOUT MY MASTERPIECE, A THING, WHICH IS PERFECT
The Simpsons has been on for 24 seasons. For most people, the golden age of The Simpsons starts in season 3 (despite one of the animators pushing his foot fetish on people), and ends with season 8. I will not accept any answers that place the golden age as starting after Homer at the Bat or ending before Homer's Enemy. Honestly, it's hard to pinpoint a single episode, as flashes of the golden age are seen in seasons 2 and 9. Season 11 is no man's land, however.
No matter when you think the show went to shit, most will agree that The Simpsons needed to end years ago. I say the movie should have ended it. Despite not being a great film, it would certainly have been a good way to go.
The Simpsons's downfall can be seen particularly well in the guest star episodes. In season 3's Homer at the Bat, the plot centres around Mr. Burns' softball team. He makes a million-dollar wager and decides to replace his employees with baseball stars. Despite having nine special guests, the episode is still about Homer. All of the guest stars are treated poorly, with fates ranging from being stuck rescuing furniture from a house fire to getting arrested for every crime in New York City. Don Mattingly gets fired for not shaving his "sideburns". Every guest except Darrel Strawberry gets taken off the team for some reason. Then Mr. Burns decides to switch Strawberry out for Homer because he's "playing the averages". Homer then wins the game, and the credits roll.
In newer episodes, the plot boils down to this: CELEBRITY OF THE WEEK visits Springfield! BELOVED THE SIMPSONS CHARACTER(S) becomes the best friend of CELEBRITY OF THE WEEK! CELEBRITY OF THE WEEK conveniently has to leave Springfield!
In summary, old episodes created a plot and put celebrities where they fit. New episodes take a celebrity and put plot where it fits. It's completely backwards.
One of the best parts of The Simpsons is the broad spectrum of jokes. In rewatching episodes I saw several times as a child, I am finding new jokes I didn't understand before. Knowledge of how jokes work also helps. Yes, writing my shitty stories in a hopeless attempt to be funny has made me enjoy The Simpsons more.
In the end, despite being bad, we can learn a lot from new episodes of The Simpsons. We learn how some jokes are just bad, and that these bad jokes will make you millions.