I think you're just mistaking "big finale" with 'Marvel Branding' or whatever you want to call it.
At the end of the day, a movie is a movie. I don't think anyone goes into a blockbuster movie in May expecting a movie breaking new grounds in story telling techniques. To argue about that being wrong is something ; to blame it as a big dumb Marvel movie is dumb.
Many movies finish with a big bang, and they're expensive and bit repetitive... but people want that. I want that in some of my movies.
Marvel has shown great restrain on TV and Netflix so far in term of scopes, because the medium allows it. They've already explored many genre throughout the super hero genre (Spy thriller in TWS, buddy comedy in IM3, Fantasy Epic in Thor 1, Space Opera with GotG, War movie with Captain America), which is something that hadn't been done or really explored before.
Whether you want it or not, it works and most movies are different.