Why is that Part 3 of Anything is almost always a letdown at best and a complete disaster at worst???
Notable inclusions:
Pirates of the Caribbean 3
(to a degree) Return of the Jedi
Star Trek III
Back to the Future III
Jaws III
Matrix Revolutions
Superman 3
Spider-Man 3 (same movie as above)
X-Men 3
Alien3
Batman Forever
GodFather Part III
Terminator 3 (How could anything follow 2? And, secretly, I like this one. Don't tell.)
Half Life 2: Episode 3
Rocky III
Anne of Green Gables (This one is for my sister!)
Shrek 3
Notable exclusions:
The Last Crusade (Though it's not perfect)
Harry Potter and the Prizoner of Azkaban (Although the movie disappointed me (yes, I know I'm in an extreme minority here))
LotR:RotK (though it's still probably my least favourite of the trilogy)
GoldFinger (though not nearly as good, IMO, as FRWL)
Planet of the Apes 3 (Escape from)
Toy Story 3
General exception to the rule seems to be when Part 2 is a total bomb, then 3 has a chance at being all right. See: Super Mario Bros 3, or Zelda: A Link to the Past, or Starship Troopers. In fact, the better Part 2 is, the worse off Part 3 generally has it. It also seems that when Part 3 is billed as "the end of the trilogy" that that makes it less likely to be good than if it's "Here's #3 and we're still making 'em!"
Star Trek is an odd example. Is Star Trek III really part 2 of the Star Trek Trilogy and not part 3 of the Star Trek series? Is that why Star Trek III isn't as bad as some and Star Trek IV isn't as good as it should be too? Did they split the difference?
(NOTE: Not to be confused with: http://originaltrilogy.com/forum/topic.cfm/Article-on-prequel-films-Note-Does-not-pertain-to-Godfather-II-which-isnt-a-prequel-its-a-sequel-with-extended-flashback-sequences-or-a-partial-prequel-to-some/post/451694/ or http://originaltrilogy.com/forum/topic.cfm/Sequel-Statistics-Chart-OR-Sequels-Suck-and-We-Have-the-InfoGraphic-to-Prove-it-OR-Anchorhead-was-right-Tell-your-sister-Anchorhead-was-RIIIIIGGHT-OR-Sequals-thx-Boost/topic/12383/page/1/)
Alright, so the list making is fun and all... but why do you think this is so common? Or is it? Have I made a mountain out of a mole-hill?