Interesting data points: Hasbro did recently authorize the creation of G.I. Joe and Transformers RPGs... by a licensee,
Renegade Game Studios. Also a My Little Pony RPG (
the second in as many years, in fact) and even a Power Rangers RPG (which Hasbro is themselves only a licensee for, so this is a sub-license). The four RPGs are all supposed to be D&D 5E based, as well.
That means that Hasbro isn't opposed to having more RPGs... but isn't interested in producing them through Wizards.
The last Marvel RPG was
Marvel Heroic Roleplaying, which apparently didn't make enough money to sustain itself, despite coming out just as the MCU caught fire. It's kind of astonishing there hasn't been another attempt...