The Marvel Cinematic Universe used to come with a near-universal seal of quality. Fandom issues aside, almost all the early Marvel projects were at least mediocre as individual films. The brand has reached a hit-or-miss era, leading some fans to abandon the franchise. Eternals and Secret Invasion were seen as ill-conceived messes, but their poor reception might be the only thing they have in common.
There are so many unique ways for an entertainment project to fail. They can encounter disasters behind the scenes, suffer destructive edits from the studio, or start from a terrible initial premise. Marvel usually makes mistakes catering to Disney's corporate greed. They break plot elements to fit future entries, rely heavily on VFX to avoid employing union workers, and demand comprehensive rewrites months before release to keep shareholders happy. Eternals has those problems but also has other, more engaging issues.
Secret Invasion was a bland mess
Some critics were very kind to Secret Invasion. It was hailed as an antidote to superhero fatigue by some. The series features superpowers, but no one wears a cape. It's arguably a thoughtless remix of elements of other Marvel projects. Captain America: The Winter Soldier featured as much espionage as Secret Invasion, but it's still a superhero movie. Samuel L. Jackson's performance gets the showcase it deserves in Secret Invasion. That's the only aspect of the presentation that works as intended. Jackson is great in the role, but the surrounding story is perfunctory, incongruous and inconsequential. The show features slightly more mature subject matter, most of which has been covered in other Marvel projects, and one excellent performance, but its nuts and bolts are unimpressive.
Secret Invasion struggles to tell a compelling story. It's borrowing its title and basic premise from one of the most iconic cross-over events in modern Marvel history but narrows its focus to ensure the brand's integrity is maintained. Take the Super Skrull, for example. In the comics, Super Skrulls capture the DNA of Marvel heroes to borrow their powers. The most iconic Super Skrull is named Kl'rt. He comes to battle with the gifts of The Fantastic Four. The MCU gives Gi'ah, a minor character in the comics, access to the Skrull Power Replicator. She has a healing factor from Extremis-enhanced superhumans like Aldrich Killian. Her strength and durability are improved by DNA from Drax, Thanos, the Hulk, Thor, and others. Her selection of powers is weaker, but it suits the MCU canon better. It's a small issue but a microcosm of Secret Invasion.
Secret Invasion's most publicized crime is its treatment of James Rhodes. Rhodey is revealed to have been a Skrull in disguise early into the series. He's an agent of the alien invaders. This would be understandable if they were clear about when Rhodey was replaced. The creators suggested that Rhodey might have been out of commission since the events of Civil War. That choice would've invalidated every moment the character experienced in Infinity War and Endgame. It's another symptom of Marvel stepping on its own work. Secret Invasion doesn't succeed by deviating from the larger MCU. It fails by staying entangled in the same pool of problems.
Eternals was an ambitious failure
Eternals has a slightly lower score on Rotten Tomatoes than Secret Invasion. A quick glance at the reviews yields words like "massive," gorgeous," and "vacant." It's a massive, absurd, bizarre science fiction epic that borrows from strange and eclectic sources. It's still a superhero movie, but the massive stakes and esoteric characters add elements that aren't present elsewhere. It's more, and somehow less, than the average Marvel movie. It's Chloé Zhao's take on the ancient aliens theory, a complex character drama, and a series of gigantic fight scenes with no time to breathe in between. Its ambition deserves respect beyond its success. Even if it didn't work out, there's no doubting the impressiveness of the attempt. What kind of movie could catch flack for making one of its central characters directly responsible for the creation of the atomic bomb? Eternals will go down in history as one of the most intriguing action films of recent memory. Not the best, but the one that inspired the most conversation.
Ultimately, the failure of Eternals is worse for the overall medium. What did the poor audience reception of Secret Invasion tell the studio? Nothing they didn't already know. The failure of Eternals is another piece of useful evidence for the accountants and IP holders. When something unique dies, it's unlikely that anything can replace it. If every ambitious superhero project flops, the studio will be happy to fill those slots with boring trend-chasing trash. It's the gradual erosion of what people love about filmmaking. Risky, unusual projects are always a gamble. If studios stop rolling the dice, fans will be left with an endless parade of Secret Invasions. Praise that which succeeds, but spare a thought for the art that fails in a compelling way.