Most hated the art-style, not the graphics per say. Thing is, some fools don't know that there's a difference. Gfx was sublime for sure. Art-style....I liked it enough, but I can see how some have contention with it. Most comic book fans seemingly desire more...vibrant and/or more animated art-styles for comic book iterations, which I get, to some degree.
Some of the design decisions weren't that hype tbh. In some cases, they could've done more and in some cases, they could've/should've did less. Like, I know lot of folks felt that Black Widow didn't look pretty enough in the face, in part, cuz they're MCU fans comparing it to Scar Jo. Hell, a lot of folks shytted on the game for the character designs not more resembling their MCU iterations. And on the other side, folks hated that they went too realistic for their looks, with even more slant to that considering they don't look like their MCU counterparts. But, comic books have always had different art styles, some more preferred than others, but often quite drastic in styles from others, so it wasn't much issue to me.
I just finished Age of Calamity (dope game!) and these gifs just reminded me that an Avengers game in that style might work. In know Dynasty Warriors isn't everyone's flavor but imagine playing out that Wakanda scene from IW, or fighting Ultron with 100's of sentries flying around 
