Name actors, and good animation probably costs more than Jack Black and Jason Momoa in front of greenscreen for a couple of days. Some dumb suit didn't think a game like half of all millennials and zoomers in developed countries have played doesn't need these big name actors.

In Minecraft Live Mojang said that live action hadn't been done before in comparison to animated projects made by players, yet discussed a downside of this in the same segment (They had to make most blocks not be a meter on each side because of actors needing to pick them up/walk on the terrain, meanwhile some blocks in the background (such as on the terrain from the trailer) are much larger than a human). Also making a trailer featuring live action characters in a Minecraft-like world makes it easy for the viewer to understand "We're trapped in a video game" without reading about the movie's plot.