Outside of the other reasons stated here, I think, more than anything it's the timing of release.

I like the FF franchise, the last couple though have come out at a time when other bigger movies were out, or it was more in the summer. Anecdotally the last couple have come out when I found more interesting things to see in the theatre and so I never actually saw them in theatre although did catch them eventually.

I'm a movie lover but I tend to reserve my theatre visits to big action movies, I like watching Drama and such at home where I can be free of distraction and comedies are kinda meh. So I get excited for blockbuster season and this year that seemed to be AoU leading the kick off.

Having really nothing else in the theatre in that genre , FF7 had complete unopposed dominance if you were looking to se a movie and wanted the big popcorn flick, for the past month that's been your primary choice, regardless of any other factor, this movie made that amount of money because it was released at the perfect moment.

Over the past few years we've seen a trend toward blockbuster season extending nearly to September when before end of july/aug was seen as the death months. Similarly the pre May months were always seen as a dead zone as well, and this movie will likely be cited as one of the handful over the past couple years, and going forward that extends the season both front and back. Marvel already caught onto this the past few years with their spring releases.

Seems like whomever can get a decent blockbuster out in march/april is going to make huge money regardless of quality, until more studios slate in to this time and create competition.