Then you & I have very different definitions of bad. Allow me to use a fellow GAFer's post as proof of my point.
Thor: 77% (critics score is 63%)
Thor 2: 66% (critics score is 44%)
Iron Man 2: 72% (critics score is 60%)
Iron Man 3: 79% (critics score is 61%)
Captain America: 79% (critics score is 76)
Age of Ultron: 74% (critics score is 72)
Let's look at the great Marvel movies:
Winter Soldier is at 81% (critics)
Guardians of the Galaxy is 85% (critics)
It's at least great to know Captain America: The First Avenger is considered great, though (by RT logic).
The point is no one wants Marvel properties to be given away to some place perceived as more competent. It's a petty move. There's no need for it. Marvel could make a good Fantastic Four movie. Another studio could make a good Thor movie.
The worst you can say about their movies is that they are bland and formulaic. They at least understand the source material and cater to their audience. Fox just shits out movies made by committee that are objectively bad and miss every target audience by a mile.
And your point about the rights still doesn't make any sense, especially considering the history of Marvel licenses.
What's wrong about my points with rights? I just want people to be consistent with their logic. If a movie is bad then say that property should be given to another studio. Marvel shouldn't be the only studio that people want to make movies at.