Why the Double Standard?

That is because the sequels usually suck donkey balls and not worthy of being called the same as the successor.

Because a lot of movie sequels are made to cash in on the original's success, not because there's more to tell. This happens in books too, of course, but it seems to be more of an exception than the norm.

For a book, it's hard to be bad when the prequels were good because most parts of the story and the atmosphere are made of your own imagination, which was built by the prequels. And thus, every new book will improve the already extisting experience.

This is not the case with movies, since they are shorter by a huge amount and the experience is mostly defined through visuals, without the need of imagination

I don't usually hold a sequel to higher standards. The thing with sequels is, a lot of the time they are made for solely one reason, money, to milk it for what it's worth and that, a lot of the time, results in it being a piece of shit, excuse my french.

With the time it takes to read a book, you absorb more of the story. Plots can be elaborated on, personalities developed and a lot of other stuff that just cant be put on film. A movie can only confer a small fraction of the whole story no matter how long, and generally are only meant for a quick bit of entertainment. A book is made to make you want to read the next in the series, movies only want you to buy crappy merchandise.

As several of you made the point - of for money - I'll give you that on some cases, but thats not the case with all sequels. I can understand people being leery about an upcoming sequel but to be completely against the film? I've known people to tear a movie to shreds and I wondered "Why didn't you just walk out and get your money back?".

To a degree I think some folks just want something to complain about. More so for the fact that I don't see much effort from them to create any form of content to entertain others. To me its hard to justify having that high of a palate with nothing to show for it.

It might be too early, I can't think at the moment but I known for a fact I've seen some sequels that compared to the first, if not were better.

Because nowadays, most sequels are just quick cash grabs because the first movie was a success.

Hmm I see what you mean, but then again movies appeal to everyone so there's a broader audience to entertain whereas with books, you tend to entertain a certain audience, people don't realllllly read something random just to see what it's like but with movies people just watch whatever, usually.

1) There COULD be this reason that books have generally smaller audience than movies - ergo less people to disappoint, less people to whine everywhere.
2) Most sequels "we" hate are those that just feel like one big money grab. Even when you make a "stupid action movie", you need to give it a moment of thought how to make it at least watchable.
3) I know I hate few books in Discworld series and I always tell people to not touch them to get into those books.
4) And last thing - one would risk stating that books are read by adult/mature people, while movies are more kids stuff - yes, big generalization, but still, when you make stuff for 13 years old you really make it differently compared to when you make it for 30 years old.