Point taken, and I see Fantastic Beasts (FB) has a sequel (FB2) currently slated for a November, 2018 release. That said, 1.) there was no Lego set issued in conjunction with the first FB film, unlike with the the first HP film in 2001, and 2.) FB and FB2, being spin-offs from the original HP with new plot points, supplies no business or marketing case for Lego to issue new sets based on the original HP, so I still don't see that happening.
Given that Lego didn't issue any sets in conjunction with the first FB film, at best it is taking a "wait and see" approach to see if it's worthwhile to issue sets tied in to the FB franchise. The first HP movie was the highest grossing film in the year it was released in and broke box office records. From Lego's point of view, making sets in conjunction with it was a no-brainer. By comparison, FB was just the 9th highest grossing film in 2016. Still a good showing for the studio, sure, but good enough for Lego to invest in? I'm still very skeptical.