Sequels, adaptations and shared universes dominate release schedules for a reason that has little to do with creative exhaustion. The decisive cost is not making the film but making people aware of it.
Awareness costs roughly the same either way
Reaching a national audience requires a campaign of a certain scale, and that scale does not shrink because the film was cheap to produce.
An original film and a sequel both need trailers in front of audiences, outdoor advertising and a presence on the platforms people use.
Because that cost is close to fixed, it consumes a much larger share of a modest film's budget than of a large one's.
A known title starts with awareness already bought
A franchise entry begins with an audience that already understands what it is, which converts marketing spend into attendance more efficiently.
An original title has to explain its premise before it can persuade anyone, and explanation takes more exposures than reminder does.
The gap in efficiency, repeated across a slate, is large enough to determine what gets made.
Financing is arranged against recognition
Large films are frequently funded partly by selling distribution rights in individual territories before production.
Buyers in those territories commit against something they can forecast, and a recognisable property forecasts far more comfortably than an unknown one.
A project that can be presold is a project that can be financed, which quietly removes originals from consideration before any creative judgement is made.
Risk is managed across a slate, not a film
Studios plan in slates, and a slate needs a predictable floor so that one failure does not endanger the year.
Franchise entries supply that floor because their downside is shallower, even when their upside is unremarkable.
Originals are then funded from whatever risk appetite is left, which is why they cluster at low budgets or at prestige scale and rarely in between.
What this squeezes out
The casualty is the mid-budget film, expensive enough to need a real campaign and not recognisable enough to make that campaign efficient.
Much of that work migrated to streaming services, where a title does not have to persuade anyone to leave the house.
The economics did not eliminate original storytelling. They moved it to the place where the cost of getting noticed is paid differently.