Now this article might get a big backlash, as Marvel fans would eat me alive if I mention DC being better than Marvel.
I just want to justify my statement by saying that I enjoy Marvel movies too, my last favorite movie was Captain America: The Winter Soldier
Now lets get to the topic: Why DCCU will be bigger and much more better than MCU?
DC comics was founded by a sole purpose of convincing kids that there can be Superheroes in not ours, but in other universes. What i mean is that even if our world doesn't have flying spandex wearing aliens, we could imagine and write one in our minds.
Superman gave people hope and was a true hero. Not just a frisbee throwing soldier, or a Norse mythology rip-off. No he was a true hero.
Once Marvel caught up with DC in mid 40's and 50's. Both companies had equal amount of people working for them and fans supporting them. But one thing that differentiated them was their creative minds. Since the war ended, DC took a whole different route, the team up comics. First Super Friends, Justice League of America, Teen Titans. The DC Comics had the definitive team up comics. But Marvel, as always, started to copy, and made their own little team called "The Avengers". I might be going off topic here but my point is that DC never lost its originality through the years. Talk about Batman, Wonderwoman, Cyborg, Green Arrow, Flash. These characters were ripped off later on by Marvel. Captain Marvel, Hawkeye, Quicksilver.
DC started the grand scheme of superhero movies, and defined its genre. With the release of 1978's Superman the movie, DC ruled the cinematic world for nearly two decades until Batman&Robin came out in 1997, destroying the now popular franchise.
However, when Nolan came on board to reboot the Batman franchise, everything changed. DC took a whole different turn. They started developing a Justice League movie, and even picked up the forgotten Tim Burton Superman Batman movie and rewrote the scripts, dozens of times. They were planning a superhero team up movie even before Marvel started working on Ironman 2008.
DC took their time to realise that a single hero franchise could do on its own, but seeing how Marvel made billions of dollar with a Cinematic Universe, they are doing exactly the same, merely 10 years later after its original plans.
Now they know how to make a superhero standalone, team up, animated, Tv show, reboots, sequels. So they will have a upper hand in terms of grand scale and commutative force