There are a great many things from which the superhero genre has moved away (to at least, some degree). Teen sidekicks. Secret identities. Hand-wringing girlfriends. Casually oblivious privilege. Some for the better, some for the worse (your mileage is almost certain to vary on some of the specifics, let's not get too hung up on that here).
There's one, tho, that I miss: The Weakness.
Now not every superhero had one. Green Arrow didn't, unless you count archery cyclic rate relative to firearms as a weakness. Black Panther didn't, unless your head-canon requires that he consume the heart-shaped-herb regularly, rather than as a one-and-done.
But a lot did, and sometimes it added more than it subtracted. IMO, losing that closes as many plot options as it opens.
It gave Iron Man something extra that using his powers drained his pace-maker. In a similar manner, (Ditko's original) Captain Atom was immensely powerful, but it waned as he expended energy, sometimes having to be content watching doves outpace him in flight. Mr. Fantastic originally grew weaker and fatigued the further he stretched, and the more complex the shapes he adopted. There was some value in Green Lantern's power being useless against some substances (although, I'll grant you that the color yellow was overly arbitrary, no matter what the metaphor was supposed to be). That was good stuff.
One of my favorites was Golden Age Starman: His gravity rod simply wouldn't work under direct sunlight. Now the "science" used to explain it (something about the intensity of our sun's UV rays) was dubious, at best; a kid with a UV lamp literally shut him down once. But it made things interesting. It confined him to operating at night. A plot had to account for his need to get stuff wrapped up and back to safety before sunrise, almost like a vampire. It made it easier for a writer to complicate his adventures, instead of having him blow into town like The Spectre and blast the issue into submission. It forced the author to write some cleverness into the character, and to rely on skills other than his ability to build and use the gravity rod.
Anybody else out there have a favorite superhero weakness?