This deserves further discussion for sure.
I'll do it at some point in the future on a blog post and will link it here.
Another interesting measure is studio funding of remakes and sequels (adjusted for inflation or as a percentage of total Hollywood's production spending) but that starts getting into blog post territory.
Up until the past decade or so there was always something that was interesting at the movies.
Not so much anymore.
The overall thrust of the "there's too many sequels and remakes" argument is that recent cinema shows a staleness/creative exhaustion in the industry, which is relying on brand recognition to cover for its failings. One creator expanding on their animated shorts to make a feature film out of them (Office Space) or a filmmaker making a (relatively creative, I think) adaptation of Shakespeare (10 Things I Hate About You), doesn't really demonstrate that, IMO. Many of the other examples you cite do. Certainly people have been complaining about sequelitis in movies for as long as I can remember (30+ years).
My own impression of a big trend in film over recent decades is the decline of comedies, especially in the family comedy/romantic comedy sub-genres. But I don't have hard data on that either.
Between The King and I (Disney animated), Baby Geniuses, Doug's 1st Movie, 10 Things I Hate About You, Wing Commander, The Rage: Carrie 2, My Favorite Martian, and Office Space, I see plenty of sequels, low-effort trash, and remakes. And that's just stuff that came out in the first three months of the year.
edit: We got a remake of Wild Wild West, a remake of Tarzan, a sequel to Austin Powers, a sequel to The Brave Little Toaster, a prequel to Star Wars, and our second Shakespear adapation of the year in months 4-6.
double edit: In 7-9, we got another Muppet movie, an Inspector Gadget remake, The Haunting and The Thomas Crown Affair were both remakes, a Universal Soldier sequel, and a Dudley Do-Right remake.
I have no interest in continuing to analyze this list, thing were just as bad twenty years ago