I think critics of superhero movies do them a disservice by just dismissing them as advertising for another movie. Batman V Superman isn't an advertisement, it's a chapter in a much longer story that has yet to be told. Maybe it's this idea of "serialized entertainment" that has thrown people for a loop. It used to be that novels would be serialized and released a bit at a time. My most recent memory of this (and it's not too recent) was Stephen King's serialized novel, The Green Mile. Since that came out more than a decade ago, it's easy to think that a whole generation (that doesn't read stuff on Wattpad or the Nifty Archive) is unfamiliar with stories being told in bite-sized chunks, released one chapter at a time.
And serialized storytelling has a lot of advantages. For one, it's kind of like a 401k investment plan. In other words, thinking of retirement as one huge chunk of money that you'll need in order to leave the workforce forever can be very daunting. However, taking it in small pieces over a great deal of time makes it a lot more palatable. The same can be true for storytelling. In our fast-paced low attention span culture, a serialized story does not ask for a lot of investment from a person. Everyone can spare ten minutes out of their day to read the latest installment.
Another benefit of serialized storytelling is that installments need to have a hook that brings the audience back. This is why in superhero movies, we usually have a complete story arc that has a definitive conclusion, yet leaves the door open for more growth.
Anyway, I guess all I was trying to say is that serialized storytelling is not advertising, and superhero movies are using the principle of it to bring together some previously impossible story arcs. Who wins in that situation? We all win because we get to sit back and watch the story unfold one piece at a time.