The Simpsons is, without a shadow of a doubt, the most well-known animated series in the history of the world.

It's inspired a generation of animators, it's a cornerstone of modern pop culture, it became a talking point in a US Presidential election, it has been a part of our lives now for almost twenty-six years.

There have been moments in The Simpsons of beauty and tenderness that are likely to stay with us forever. The ending of Mother Simpson, when Homer sits silently on the hood of his car after his mother disappears again, watching the stars whilst a beautiful piece of music plays over the end credits. Everyone has a favourite one-episode character. Hank Scorpio. Poochy The Dog. Molloy the Cat Burglar. Cecil Terwilliger.

For all these moments that we laugh and cherish, it's time we said goodbye to it at long last and move on.

What began as an alternative to the mainstream trash - creator Matt Groening's own words, by the way - has crossed over and become just that. Trash. It's almost a cliche to say it nowadays, but The Simpsons stopped being funny, stopped being good in and around the tenth season. Ten years. Most TV series nowadays are lucky if they make it that far and remain consistently entertaining for that long.

Take Friends as an example. It ran for ten seasons and had probably four, maybe five good seasons. Apart from a few spotty blips in quality in the later seasons, it was mostly done in and around the time Chandler and Monica hooked up. After that, it spiralled off into various shark-jumping storylines. Honestly - why did Joey and Rachel ever, in a million years, hook up? It was desperation on the part of writers and showrunners who were desperate to keep the train moving and actors who were either too lazy or too greedy to care.

The same can be applied to The Simpsons. Can you honestly remember the last time you were remotely excited about the prospect of new episodes of The Simpsons? We sure can't. Sure, they've have a cavalcade of celebrity cameos, themed episodes set in the likes of London, Dublin and so forth - but have they actually made you watch them? Probably not. Much like Friends, they're reaching for something that just isn't there anymore.

It's not as if The Simpsons hasn't tried several times to reinvent itself, to make itself something audiences will want to watch. The endless crossovers, the cloying attempts at addressing societal issues now seem desperate. The Simpsons covered just about everything within ten seasons. You had deep, introspective episodes about the meaning of marriage, e.g. when Homer meets his spirit guide (voiced brilliantly by Johnny Cash) and tells him to find his soulmate. You had an intriguing glimpse at the nature of the soul when Bart agrees to sell his own to Milhouse for an inflatable dinosaur. And, of course, you had an episode where Homer goes to work for an evil billionaire that's uncannily like Larry Ellison.

What have you got now? Crossover episodes.

In 2001, longtime producer / showrunner Al Jean said that "the hardest thing at this point is just thinking of fresh ideas. People are so on top of things that we've done before, so the challenge now is to think of an idea that's good, but hasn't been seen." That's fourteen years ago. We've had fourteen years of tired, hackneyed ideas and couch gags and references to jokes that show a writing team and showrunners who aren't leading popular culture so much as desperately following it to stay relevant.

Think back to the earlier seasons. The Simpsons was so far ahead of the curve that when the likes of South Park and Family Guy came, they had to struggle to keep pace. Now, instead, Family Guy has plummeted to depths heretofore unheard of in television history whilst South Park, though still entertaining, now embraces a culture of proselytising to its viewers.

So, what's the remedy? Just drop The Simpsons? Just like that? The answer is, simply, yes. It's had a good run. It's served its purpose well and done the state some service. In 26 seasons, only 10 have been worth watching. The ratio has well and truly turned against it so that now it sullies what has come before. When you watch an earlier episode, don't you find yourself wishing it maintained this level of ingenuity and smarts? Of course you do.

But what show would be allow to continue on for so long without a threat of cancellation? Absolutely none. At some point, a hard-nosed studio executive would step it, gut the entire thing and sell off the assets to whoever was buying. But no, The Simpsons has lingered on in a life-support machine for far longer than it should have. If this were any other show on the face of the Earth, you can be guaranteed that the show would have been cancelled LONG before it got to its current, bottom-scraping levels.

It's unrealistic to expect any TV show to last that long and still be as good as it can be. What kept The Simpsons going for 16 years past its sell-by-date is simple greed. Nothing more, nothing less. Greed on the part of the cast, the producers, the showrunners and the studio. It was and continues a cash-cow for all concerned. Nobody wants the gravy train to stop. And by sacrificing quality and dignity for the sake of money, The Simpsons continues to be that which it set out to challenge all the way back in 1989 - trash.