I am okay with the period settings in general, but I don't want a ten year jump because it creates issues in plausibility. XM:A was set in the 1980s because they wanted to finish out an arc for the quartet from First Class. Although Fox has clearly tried to take advantage of Jennifer Lawrence in marketing, I don't think they chose to do another prequel as a result of her.
Drew McWeeny wrote in his review of DOFP, "I like that the majority of the film deals with the younger cast. While I like the cast they put together for the first three films, I think McAvoy, Fassbender, and Lawrence brought a huge new energy to the series, and picking up with their stories is, I think, the most compelling place for the films to go at this point."
If a movie critic felt that way, maybe the creators felt like that too.
Of course, Apocalypse still had problems. And Fox is a business. They also didn't have the old cast under contract, and so scheduling issues come up. Costs would also rise with that consideration, because some of the players could threaten to walk. One reason DOFP was expensive was the salaries of the casts added up.
I suppose you could call it "Fox's obsession," but it seems like the choice of Singer and Kinberg.