DC is putting up a brave fight. They've got awesome heroes, they've got cool villains, they've got an interesting dynamic with all the different families that they have, but there is no way that DC is going to be able to take on the Marvel Cinematic Universe. It's too big a challenge for anyone. Let's take a gander at why, shall we?
(DISCLAIMER: This article is going to commit the grave internet crime of having an opinion. That's all this is. Feel free to disagree with me, and post your rebuttal in the comments.)
Starting later puts DC at a huge disadvantage.
DC's universe officially started five years after the MCU, with Man of Steel in 2013, instead of Iron Man in 2008. That, one could argue, gives DC a chance to see what people respond well to, and what they don't like. There's a bit of a problem there though: DC has a lot of examples of what people respond well to, but none of the Marvel Movies were even really below average. Sure, Iron Man 2 was really just killing time, but it still made sense, it was still entertaining, and was still well made. You can learn from success all you want, do all the same things, make all the same moves, but all that will get you is a participation award.
Another interesting point about this late start thing is that Man of Steel wasn't supposed to be the first movie in the DCCU. Green Lantern was. Green Lantern was released in 2011, three years after Iron Man, and also after the Hulk, it was being produced at the same time as Thor, heck, it was released three years after DC's own Dark Knight! It still sucked. DC had a chance to learn from Marvel, it even had a chance to learn from itself and establish it's own identity, but it failed to do so. It tried too hard to be Iron man, with the sarcastic protagonist and the lighthearted tone, and it failed miserably.
"Dark" and "gritty" is not the same as realistic, and even if it was, do we want "realistic" superhero movies?
I see this a lot as an endorsement of DC, and I don't really get it. I want to like my superheroes, to sympathize with them and to understand why they are doing certain things. I understand why Cap and Iron Man are fighting in Civil War, they've established that Cap is against preemptive action during Winter Soldier, and they've shown that Iron Man wants to stop every crime before it's committed. I understand what the conflict is, and I can sympathize with both people because I know them, and I like them. I don't like this Superman, he's depressing, he's boring, and he's hypocritical. That's not realistic, that's just "dark" and "gritty". It doesn't have a purpose other than to be "dark" and "gritty".
Super heroes are modern mythology. They can be dark, sure, but they're meant to be human, to have emotions, to smile, to have fun, to make mistakes, and to learn from them (can you tell I'm not a huge fan of Batman?). I don't want my mythology to be realistic. I want it to make sense within the boundaries that it sets for itself, sure, but I want it to be fun, to have dance-offs with alien tyrants when they're about to destroy a planet, to go for schawarma after saving New York. I don't want my heroes to be more mournful about killing an alien tyrant than he is about a DBZ-style air battle that killed hundreds of thousands of people, if not millions. Maybe that's just me, but I don't think it is.
The Avengers exists.
This is the simplest and, I think, the biggest knock against the DCCU. The Marvel Cinematic Universe has the Avengers, and DC doesn't. The Avengers was the movie that solidified the MCU, and is probably the most iconic super hero movie of all time, with the only real competition being The Dark Knight, which, really, is kinda debatable. After all, the Dark Knight didn't have this:
And now that Marvel has that moment, if DC tries to do that all they're gonna get is "Hey, that's like that scene in The Avengers!" Which, let's face it, is kinda bad for brand recognition when you're getting that kind of comparison with your direct competition.
The Avengers gives so much credibility to the MCU that I really don't know if DC can ever come close. It's fourth all time in box-office sales, and it's sequel is sixth. Man of Steel comes in at eighty-second. That's behind five of the twelve MCU movies, one of which was of an IP that literally no one but hardcore fans had ever heard of. It established Marvel as a kid-friendly brand that everyone can enjoy, while DC seems to be going for that young-adult to middle age demographic, I think they're going about it in the wrong way, but again, that's my opinion.
I want the DCCU to be good, I want to like these movies, and I don't think they should copy Marvel, but I also think that they've got way too much ground to make up, don't really understand why we love super heroes, and that The Avengers alone is just too much for the DCCU to overcome.