The producer cites Warcraft, but there is no shortage of similar films that were intended to launch franchises only to become jokes in hindsight (heck, we’ve written whole lists about them, which are far from all-encompassing).
James Cameron has a point in what he told Digital Spy in that regard.
Ambitious movies that are clearly intended to set up sequels and start franchises become punching bags when they fail spectacularly, making any premature movements towards a sequel look like a foolhardy move borne of hubris.