MCU Villains: Why so controversial when criticised?

Scarecrow was my favorite part of a Batman Begins by far. Whenever I watch that movie, I look forward to his scenes the most. He may have possibly been the "creepiest" villain in a comic book movie and I think Cillian Murphy did a phenomenal job. He's my second favorite villain in Nolan's Batman trilogy next to (obviously) The Joker.

But, as others have pointed out, he couldn't possibly rank among the "top tier" of comic book superhero movie villains due to his limited screen time, presence, and the fact that he was basically a lackey playing a small part in the grand scheme of the true main antagonist. And his appearances in the other two movies were more like cameos, which weren't really even necessary. I would have loved for him to have been the primary villain or at least had a more prominent role, maybe as the second in command next to Ra's, but the whole theme of the movie very likely would had to have been drastically different for that to have been possible. His role was more comparable to secondary antagonists with less of a presence like that of Klaue, Shocker, or maybe even Sabertooth.

And, I don't know, I seem to see many people praising Doctor Octopus from Spider-Man 2 and ranking him among the likes of Loki, Thanos, Magneto, and Ledger's Joker quite a bit. I'm not saying that's my opinion either, not at all. As great as I think he is, I actually wouldn't put him in the "top tier" myself, and actually have a few issues with the way the character was portrayed, excellent performance aside. He seems to be pretty high up on most top superhero movie villain lists, though. And, from what I've seen anyway, he seems to commonly be regarded as one of the absolute best.

This whole thread got me thinking, has there ever really been a superhero movie in which the hero and villain were equally as interesting, well developed, compelling, etc.? And I don't just mean in the MCU, but every superhero movie ever. It seems like most, if not all, of them either have a hero that's done really well and a bland villain that's only a plot device, or a villain that far overshadows the hero. There are several great heroes and villains in the history of superhero movies, but has this ever really been done in the same movie? I'm sure there are many films that have a great hero/good villain (and vice versa) or whatever, but I'm asking about ones that are on the same exact level. I'm only talking about movies with one primary hero and one primary villain, so Xavier/Magneto doesn't count.

As others have already pointed out, a good percentage of the MCU has done their heroes extremely well but haven't always had an equally well done villain for them to face off against. I don't think there's ever been a terrible villain in the MCU per se, but often they usually don't compare to the hero. This is very evident in all three Iron Man movies. Movies with a team of superheroes assembling together aside, and counting only solo hero movies, this usually seems to be the case. I guess the closest would be Thor and Loki (Loki of course being generally regarded as the best villain in the MCU), who are both done very well and have a well established relationship and conflict between them. Pretty much every movie they are in together have them both done very well and possibly equal. Another worthy candidate would be in Homecoming where the hero/villain dynamic between Spider-Man and The Vulture was by far my favorite part of the movie.

And then of course there's the other extreme. Nicholson's Joker heavily overshadowed Batman, as did Ledger's, even though the Dark Knight was well portrayed in those films, nonetheless. I'd even say the same for Zod with Superman in Superman II (and possibly even Man of Steel). I really enjoyed Black Panther but I'd be lying if I said that I felt that movie sort of suffered from this as well. Not only did Michael B. Jordan's performance as Killmonger mostly upstage the hero, but I even found him mostly sympathetic and was mainly on his side for the majority of the movie.

I'm sure there's probably an obvious example I'm missing here, but has there ever been a superhero movie where both the hero and the villain were portrayed with the exact same level of greatness and focus? Aside from Thor/Loki and Spidey/Vulture (the two possible examples I can think of), that is? I'm probably wrong, and I hope I am.

Or protagonist which is the point, it's sort of meant to be a toss up between which side you see as being in the right, if you side with Cap it's easy to see Tony as being the guy trying to wash blood off his hands by surrendering control to a higher power and then trying to enforce this on others, on the other hand if you see Tony in the right you can easily see Cap as a hypocrite who believes he has rights above anyone else and who puts his personal feelings a head of anything else and remorselessly ruins other peoples lives to get what he wants, or you can see them both equally heroic or villainous.

Yep, you nailed it. I knew somebody would. I can’t believe I forgot about all those examples, especially Batman Begins. I would add Spidey/Doc Ock from Spider-Man 2 as well. I’d also argue that Winter Soldier didn’t have much of a personality or characterization, but within the context of the movie that made perfect sense and was to be expected.

In the case of The Winter Soldier, we had already gotten to know him prior as plain old Bucky Barnes before the brain-washing, so we walked in with a ready-made attachment to him. 

I know you were talking about all comic book movies as a whole. 
I agree, Zod was definitely the best of the Reeve Era villains. I loved how Stamp chose to play him as someone who takes himself WAY too seriously. 
Dirty Harry is definitely a good example. The only other ones that really spring to mind would probably be upper quality Shakespeare adaptations, and probably the original "Die Hard."

I think it helps that Die Hard put a lot of focus on getting to know the characters by the things they say and do over focusing on rich backstories. We know what we need to know about them soon enough, and the filmmakers and actors are skillfully enough in concisely summing what their characters are about to get a lot out of just about every scene. 
...Also explains why few action films have, let Die Hard sequels, have managed to recapture that. That had to take a lot of work to get right.

I'd throw Spider-Man Homecoming into that.

I was equally invested in Peter and Vulture.

I'll put the scene in the car up against anything in any superhero movie...and against a whole lot of regular movies too.