Personally, I think BvS was set up to fail from the get go with the media with a damned if you do, damned if you don't standpoint.
It made $870 million worldwide. It's being labeled as not being a blockbuster because it didn't reach $1 billion. I may be mistaken, but I believe Deadpool made somewhere in the $600 billion range, and that's being called a hit and a blockbuster. Granted I realize Deadpool is nowhere on the same level as Batman and Superman. Even if BvS did reach one $1 billion though, what's next? It didn't reach $1.5 billion, so therefore, it's a failure?
It's not enough like the way Marvel does things. I'd almost be willing to wager that had BvS came out after CW and used Marvel's technique, it (and DC in general) would have been slammed for essentially being copycats of Marvel and just ripping off what they do and not coming up with any style of their own.
I also even read an article recently that now instead of slamming the film (since apparently that's been done to death), their new target is to now apparently attack the people who liked the film. I think the title of the article was something like, "For Those Who Are Defending BvS, You're Only Making It Worse". To put it succinctly, it essentially stated that critics didn't like it, it didn't make $1 billion at the box office, so just admit that it was a bad movie and you're only making yourself look stupid by trying to defend it if you enjoyed it. As I've mentioned before, I think for a lot of people, it's much easier to be a follower than a leader because if you just simply go with the grain, the status quo and do what everyone else is doing or saying, then it requires less explanation on your part than if you dissent. Similar to what Black Widow did in CW.
I don't think anyone is saying it's a perfect movie. No movie is perfect. I think a lot of people are just simply asking was it really THAT bad as what people are making it out to be? I mean THAT bad? While at the same time, there are many people out there acting as if CW is indeed a perfect movie.
I really think a majority of the reason why DC characters are scrutinized more than Marvel characters is because there have been numerous major portrayals of these characters already on the big screen. Therefore, people have a certain adaptation that they like and are attached to and consequently, it may affect their ability to accept and enjoy any other rendition of the character that they don't feel matches up to their particular favorite rendition. Whereas with Marvel, there really have been no previous major portrayals of those characters. There's no measuring stick, so it's easier to accept these for what they are. 20 years from now when they're made again, Thor will be compared to Chris Hemsworth, Captain America to Chris Evans, Iron Man to RDJ, so on and so forth.