The reason people hate this movie so much is simply because it's another sequel. that's it. It's not as memorable and original as the first film (because it's a sequel) so people automatically hate it just out of habit.

Agreed

99% of the characters in it are awful and no ones cares if they die

All this movie was was a long chase scene with no character development. The only good things about it was the Spinosaurus, and Dr. Grant and Ellie Sattler returning. Other than that, this movie sucked

Why is it hated so much?

• Uninteresting plot full of cheap contrivances
• Characters balance between boring and extremely annoying
• Weak effects and CGI especially compared to JP & TLW
• General feeling of B-movie/low production values
• Too short

• The Spinosaurus is cool
• The Pteranodon scene is well-made
  BTW, The Lost World is better than JP3, but it has its own problems too.
  For within each death there is always a new life, a new beginning - Dillon, Alien 3

The beep fight between Rexy and beep bad writing, bad execution, and overall a very inferior film to the others.

Why is this one hated? Mainly because of annoying one-note characters, an uninspired story, and weaker direction compared to the first film (though to be fair, most filmmakers would come off as lesser compared to Spielberg). Sure it had some decent effects, a few cool action scenes, and Sam Neill was good as always. But basically a big budget B-Movie that wasn't as fun as it should have been.

IMO, this is a good movie.
Discord: "Wait a minute, where's my throne?"
Fluttershy: "I don't think you're quite there yet"

I think the question was why? Why: for what reason or purpose. That is the definition of why, people say it's the worst one. I don't agree. I think it's between The Lost World and Jurassic World. (which surprisingly the latter is generally liked.)

Because of groupthink.
Take people that haven't seen this film nor have heard the Jurassic Park community's opinion on it (or rather, the opinion of the koudest), and I guarantee you that there would be less of them calling Jurassic Park III "terrible"/"awful"/etc
It is a tale told by an idiot, full of sound and fury, signifying nothing
.

Why is it hated so much?
Because it's the worst one?

It seems more likely that Lost World wasn't that great. Because Goldblum's character kind of changed. Some sequences were nice but that gymnastics raptor take down was pretty stupid.

i loved JW but i love this one too. The Lost World is the one that makes my eyes roll into the back of my head.