Christopher Tolkien was blocking a lot of things. Even the Jackson films sneaked by and wouldn't have been made of he could have stopped it.

He's dead now, and the new heirs to the rights like money. They also have about 20 years before the copyright expires. Which isn't that long; that's about as much time between now and the Jackson films. To keep ahead of the clock, they're greenlighting a lot of garbage and risk running their franchise into the ground.