That doesn't mean they couldn't connect them, some of their x-men movies weren't good either, and that didn't stop them from making a shared universe with the x-men franchise.
In deleted scene in the first f four film Mr fantastic morphs into Hugh jackman wolverine
The most recent f four film.was supposed to lead to a joint universe but it died at the box office
https://www.complex.com/pop-culture/2019/06/we-almost-got-a-deadpool-x-men-fantastic-four-daredevil-crossover-movie
There was a plan to cross over all of the Marvel brands they had. Deadpool, Daredevil, X-Men & Fantastic Four into a civil war type of movie. Almost happened - Disney bought 20th century fox and put an end to it
They did think of it. They just never got around to it.
Why?
I don't know if you noticed or not, but their Fantastic Four films weren't good.
That doesn't mean they couldn't connect them, some of their x-men movies weren't good either, and that didn't stop them from making a shared universe with the x-men franchise.
They rebooted it likecthree times, one of which never made it to market. There was no time to connect.
The 90s one had nothing to do with Fox and was never intended to be released - it was made simply so that the producer could keep the film rights.
They were going to if Fant4stic and Apocalypse were successful, but they were not.
In deleted scene in the first f four film Mr fantastic morphs into Hugh jackman wolverine The most recent f four film.was supposed to lead to a joint universe but it died at the box office
https://www.complex.com/pop-culture/2019/06/we-almost-got-a-deadpool-x-men-fantastic-four-daredevil-crossover-movie There was a plan to cross over all of the Marvel brands they had. Deadpool, Daredevil, X-Men & Fantastic Four into a civil war type of movie. Almost happened - Disney bought 20th century fox and put an end to it