Depth estimation from cameras is challenging. I've seen recent research in generating depth maps using camera arrays, and even with precision camera calibration

Depth estimation from cameras is challenging. I've seen recent research in generating depth maps using camera arrays, and even with precision camera calibration and state-of-the-art techniques, there are typically many glaring artifacts in the resulting depth map. It might be that cameras introduce enough noise and artifacts into the mix that its not worth integrating them at this point.