Series that suck after the first few books

Why would the later books in a series be considered bad if they were written by the same author who wrote the initially good books of that series?  It's the author's story as the author intended.  Surely, the extra books add to the narrative as a whole.  I cannot see why later books in a series are considered something to ignore, when the earlier books were considered excellent.

Jack Whyte's Camulod Chronicles, Robert Jordan's Wheel of Time, Orson Scott Card's Ender series, Terry Goodkind's Sword of Truth, Tom Clancy's Jack Ryan novels, Laurell K. Hamilton's Anita Blake, Anne Rice's Vampire Chronicles, Christopher Paolini's Inheritance, and even series with rabid fandom like Left Behind or Twilight, tend to regard the first book as excellent, up to about the third book of the series, and then notice a tremendous drop in quality.  Why?

Because these authors are not that good at writing, and couldn't keep up whatever it was that made people like the books. Dune is another one. Judging by Quofum, Alan Dean Foster is a terrible writer now.

It's true.
Maybe the authors are not as passionate about the story by the third book. Artists sometimes describe their art as something that's inside them that just has to come out. Maybe there's no more story to come out but the story on paper hasn't come to an end. So the authors want to bring the story to a close even though they've lost what initially drove them to write it.

Inheritance was never good.

Sword of Truth started going downhill halfway through the FIRST book.

>>5
Cosign.  I love how Goodkind set up that race of fairy-like creatures and then NEVER REVISITED THEM.

>>4

You know how it had a ton of fans.  Go read the Amazon reviews for book three and even they hate it.

I disagree. I think the Wheel of Time series got better. It was not until the fourth book that shit actually started happening. The first three books were really just giving us an idea of what the characters were like and what world they lived in. 4-7 was when shit was getting ready to go down. People were priming the grounds, Rand got his fat ass armies, whats her name died, the bodyguard fell in love with that girl and helped her kill all those niggers back in the hometown, and the magic girl became head of the outlawed blue and green wizards. then books 8-11... fucking shit gets thrown down, the seanchan straight up invade from their continent, matt falls in love with the queen of the seanchan and works his magic on her, rand goes super saiiyen level 9. Feels good

Maximum Ride. Good for the first 2. stopped halfway through the third. now they're fighting global warming? wtf?! is global warming lik a monster or something, nd they gotta team up with Al Gore??

>>8

Could the whole story be told just as effectively in less than seven books?

Who the hell said the Ender series gets bad? the later books were awesome. Just not written for fifth graders.