I disagree. ACR and LR are about trying to perfect the image rendering process, not the capture process. My view is that optimizing the capture process (e.g., with ETTR) should be done in the camera, and the tools & feedback mechanisms that you need to perform ETTR optimally should be provided by the camera, not the post-capture image processing software.
I think that most would agree that exposure should be gotten right in the camera when one can make adjustments as necessary for optimal image quality. Unfortunately, the camera makers have not provided us with the tools and it is necessary to address some of these issues in postprocessing. Whether or not channels are clipped is of prime interest and photographers need a way to assess this, either with the raw converter (Rawtherapee already offers a raw histogram) or with another utility such as Rawdigger.
Requesting a raw histogram in ACR is not unreasonable.