By many measures Marvel Studios has been a major success story. What began as an experiment to see if Iron Man could make it on the big screen has turned into a whole tapestry of films which tie into each other. This success was not guaranteed and I argue it Marvel Studios has been damn lucky so far. Currently they risk their luck running out and imploding upon their own lofty expectations. But how? By not investing in the tools of the trade - good writers and directors.
Recall that the first Marvel Studio film in the Cinematic Universe was Iron Man. Who directed that film? Happy Hogan himself, Jon Favreau. Not a fantastic director by any means, but cheap and pliable. Marvel got lucky in that the film was successful with those parts, taking a risk on a recovering Robert Downey Jr. who was past his prime.
Years later and we have a history of films directors and actors, which all point to the same conclusion - hire cheap and hope for the best. Marvel again got lucky with James Gunn and the Russo Brothers as their filmography was no guarantee of a good film, but they were cheap and pliable.
Recently, Marvel Studios has gotten competition from Warner Bros who owns DC Comics and is crafting their own comic book-based super-hero cinematic universe led by Superman and Batman. Who do they hire to make their films? Zach Snyder, David Ayer, James Wan, the writers/directors of The Lego Movie and Ben Affleck as writer/director/actor. Warner is investing heavily in actual established talent. Just look at the cast of Suicide Squad which casts former tent-pole actor Will Smith as just one of many popular actors in an ensemble cast.
Today comes word that Marvel Studios is breaking away from Marvel because of limits on costs and creativity. So Disney is not stupid and has seen what Warner Bros. is doing and realizes that Marvel needs to actually invest in their films to guarantee quality. This is a good development for the studio, but the damage has already been done. Doctor Strange and Spider-Man have already had directors with spotty (or non-existent) track records attached to them. If those film bomb, Marvel has no one to blame but themselves. I still mourn the Edgar Wright Ant-Man film I never got to see and will continue to for the rest of my life.