Superman II - The Dark Knight - X2 X-Men United - are all great examples of films that were better than the first. Sometimes sequels can fix what was broken. Star Trek: The Wrath of Khan and The Wolverine both come to mind as films that outshine their predecessors. I didn't hate Star Trek: The Motion Picture, and I didn't love X-Men Origins: Wolverine - but the sequels blew them away.
Kevin Feige of Marvel Comics has stated that Iron Man movies will continue to be a thing. "I believe there will be a fourth Iron Man film and a fifth and a sixth and a 10th and a 20th." While that may seem like a large number, since 1966 there have been 8 batman films. There are now 23 James Bond films to date and Skyfall is considered one of the best (a successful sequel title according to angry nerd). I believe it heavily depends on quality, a willing audience, or both. David Eddings Belgariad and Mallorean series comprised 10 books that included the same main characters, and I loved all of them. While I haven't read them in years, it looks like Piers Anthony is now up to 38 Xanth books!
I get antsy with my writing, excited to share more Angst but at the same time I really look forward to wrapping it up so I can tackle other stories. I have no intent to stop until this series is done, or rush through to finish it - but there this other idea I have for Angst that I may need to tackle one day. I think would be a lot of fun if everyone hasn't suffered burnout by then.
New stories versus sequels, which do you prefer? As for Pixar, they have my permission to stop what they are doing and get busy with Incredibles 2!