To be perfectly honest, most of the criticism about brucenat has come from REALLY irate Nat/Clint shippers that didn't get what they wanted. Like, I'm trying to take their criticisms against the ship seriously, but then they blatantly ignore the possibilities that have been there since the 1st avengers film and all the evidence now and I'm like ???do you buddy, but don't say shit like "Natasha's character has been degraded by a love interest" when you're panting for her to be with Clint.
there are a lot of bitter shippers, yes, but there are people who just…idk, they have specific ideas of how MCU Nat should be, regardless of how she actually is.
the comics have to go on indefinitely but the movies have a beginning, middle, and end - we don’t want nat to be static! she doesn’t have to be an ice queen forever! we can learn about parts of her she didn’t share with us before! and her development over the four movies she’s been in has been consistent and believable.
a great example of the difference between comics nat (or at least some versions of her) and mcu nat is the controversy discussed in this post.
basically, as much as I like comics nat (or rather, certain versions of her), I will always like mcu nat more. because she is allowed to grow and change and evolve and deal with her trauma in ways comics nat never really does because none of all that will be retconned or changed for a different run of comics - her story will have a beginning, middle, and end.
and honestly the jump from avengers to tws nat was a lot more jarring than the difference between tws and aou nat, who seem like the same person lol
nat was a lot more reserved and quiet in avengers, but there was so much going on underneath the surface. I love Avengers Nat. I remember the first time I watched TWS I was weirded out by happy, jokey Nat who seemed so close to Steve when they barely spoke in Avengers. But I just accepted that they’d been working together for a while and she’d opened up and we were seeing a more comfortable and friendly side of her. and that translates well into what we see in AoU so I’m not sure what people were looking for. I saw almost no difference between TWS and AoU Nat other than the fact that Nat decides to make a move on a guy for the first time lol