Movie theatres in the Netflix era need spectacular and bombastic films in order to draw a crowd. The kind of stuff that doesn't translate well on a 55 inch TV.
It was renewed within a month of release.
This is a franchise where individual movies cost $150m+ to make. I can see why a studio wouldn't be willing to greenlight all of it at one go, especially given how the previous adaptation attempt at the same franchise was not received well.