Anyone else thinks it's funny how everyone agrees the ending sucks ass but it's when they didn't get something they want? Like it took certain fans seeing that MHA was ASS was with Tomura's death. But now people don't like MHA's ending because Midoriya didn't want to join Bakugo's agency and Bakugo kind of looked sad about it. Like oh my Loooord. I swear people do not pay attention unless it's something like.
This is often the case for a lot of works. People, (and I'm including myself in this), tend to not realise when something is bad as it happens, only when it ends.
Of course, this isn't the case for everyone. A lot of people noticed how incompetent the storytelling and writing was, but a large portion of the audience didn't have any issues until the ending.
This is both because the final war saga was full of flaws, whereas the flaws previously were more spaced out, AND because the main demographic is young boys. Not just that, but MHA soon became the introductory anime to many.
Because MHA is so closely based upon western tropes and action, being mainly inspired by Marvel and DC, it was the anime to ease new watchers into the anime medium. People who have no idea what other anime are capable of telling watch MHA, and it's great! It's flashy, everyone has superpowers, it's funny, it has dark content, it's not afraid to kill people off...
But, well, when all you've seen is MHA, all you can compare other anime to is MHA.
Young kids who aren't concerned with and don't know how to look out for all those flaws, and people new to the scene who don't know how other anime compare.
Horikoshi spent a long time giving the villains a sympathetic backstory, explaining exactly how they ended up where they are, and he offers no solutions.
There was certainly a level of lip-service paid towards it. But nothing actually put into play.
The HPSC is shown to be corrupt, raising child soldiers and driving Nagant off the deep-end, but nothing is done or even planned to abolish this corruption. Instead, Hawks becomes president over the very company that abused and groomed him.
Quirk Marraiges were made illegal far before canon, but Endeavour proves that they're still an actual thing. What is done to circumvent this? Nothing. Not even an activist group.
Endeavour, in general. He abused his kids, neglected them, abused Rei and drove her insane. Everything is brought to light. But nothing changes. People don't come to the realisation that heroics is a job, not a state of mind. They just forgive Endeavour because 'hE cHaNgEs'.
Mutant discrimination. What is done to help mutants become more accepted? Nothing. Shouji just yells at them that violence isn't the answer, but there's nothing actually put into play to help mutants.
Quirk discrimination in general. People with weak or 'villainous' quirks are treated like shit, (apparently). What is done to help them? ... Oh, yeah, NOTHING!
There were many early signs that MHA was going to bad. I mean, the QAT is even more biassed than the entrance exam, but Aizawa is painted as being a fair teacher. At least the entrance exam placed value on having heroic spirit with rescue points - Aizawa's QAT favoured anyone with a physical quirk.
The second heroics lessons was a simulated battle in an enclosed environment, rather than, oh, you know, learning how to fight. Bakugou nearly kills Izuku, and Aizawa just tells him to grow up.
People ignored the signs, and I did too for while, because of that hope that it would improve over time. Because the world was interesting, and it seemed to be developed.
It was not, but the minor level of lip-service made it seem like it was.
People flipped out when Izuku rejected Bakugou's offer to be his sidekick, as if that would have been a satisfying ending. People flipped out over IzuOcha being confirmed, despite it being heavily implied since the beginning.
People have turned on MHA because it didn't give them the ending they wanted. That's not to say that the ending wasn't bad - it absolutely was. But not for the reasons people brought up.
The world has barely changed from where it started, Izuku isn't even allowed to work his way into heroics, hero rankings are still a thing for some reason, the HPSC hasn't changed, and it just felt like a wasted journey.
And that's what MHA is, in the end. A wasted journey.