If I may, I think that different tones in the same universe can match. It just all falls down to the writing when it comes to make a believable shared universe/crossover.
Look at Arrow and The Flash on the CW. The former is a ''grounded and gritty'' action show whereas the latter is a way more light-hearted and colorful sci-fi fest. However when they crossover, it works and nobody's being stripped from their show's characteristics. They actually resonnate even more.
Same thing with four of David E. Kelley's old TV shows. They shared the same universe and were even set in the same city and yet they were all VERY different from each other, tonally speaking. The Practice was a dark and heavy drama, Ally McBeal was a goofy and over the top dramedy, Boston Public was a light-hearted and ''realistic'' drama and Boston Legal was just... all over the place (which was a GREAT thing !). The multiple crossovers could have been horrible tonally but they never were. The writers just knew how to be clever and how to bring those ''worlds'' together without betraying them.
So, the Marvel Studios formula works very well but I think that it's possible to take another approach to the shared universe business.
As for the FF teaser, the more I see it, the more I love it and wanna see more !