I dont want Marvel to be darker, or even more serious. I just don't care about Joss Whedon directing those movies and i also don't want them to be too campy. Winter Soldier and the first Iron Man had a great balance. Of course WS had a more serious tone but still has what makes Marvel...Marvel.
It's like how a Green Lantern movie shouldn't be made like 2011's. That was Warner Brothers trying to make some kind of Marvel movie and it didn't work. Superman and Flash shouldn't be as dark as Batman either but they need a balance. Im not interested in seeing a Flash movie because i don't care for his villains or supporting characters, but i realize that it needs to be lighter. Does it have to be ALL light though? No. I still want some serious, dark stuff. Same with Superman, just only some of the time. The light should probably outweigh the dark but you need both. Or at least i want both.
The tone of Ultron's trailers fits as a sequel. The stakes are higher and it sets up the crumbling of the Avengers. But i still don't care for the direction, or some of the characters (Hawkeye, Ultron & his faceless army (again??), Quicksilver (the dull version). Pretty sure we'll finally get the jokes when we see the full movie though.
Im sure the tone of the Batman v Superman trailers will be dark as hell with a lot of great visual treats. And that fits this universe. Once we see the movie, i hope we see the lighter side of Superman though.