Well, to answer the question in the title, it's because Marvel Studios was only tangentially involved. However, the issue plaguing Morbius are multitudinous. For starters, did anyone really want a Morbius movie? Sony has greenlit an array of films starring the wallcrawler's foes in their tenacious- and ill-conceived- attempt to launch a Spider-Man cinematic universe. Now, this idea is stupid for a variety of reasons.
- If you make Spider-Man's villains into protagonists, they become likable and consequently destroy the hero's rogues gallery.
- Spider-Man's universe is too small to furnish an MCU-style film franchise.
- And if you have to make a Spider-Man cinematic universe, why don't you make movies about his allies? Black Cat? Silver Sable? The Slingers? Prowler? It's not that hard, guys.
In any event, Morbius is now the owner of the biggest second-week drop in profits for a superhero movie ever. Despite the film being an awful idea from conception, it takes an impressive amount of negative word of mouth to substantiate a drop that swift. What happened between the reels to make Morbius such an abysmal turd?