In Pacific Rim wouldn't it have made sense if the breach was one way

I was thinking, would it have been more secure if the Precursors and had set-up the breach to Earth in such a way that it would allow a kaiju to enter earth but not return back.

Their aim was to destroy human population and in most of the fights shown in the movie, a kaiju fights till it dies. Secondly it does not make sense to bring a kaiju back after couple of fights, when it can cause more damage if it continued to attack human habitats. So is the feature which allows outsiders to pass through the breach a security failure?