Yes, potential brightness correction in post is a compromise with the potential extra DR, depending on your workflow. I shoot Raw+Jpeg and fine tune all of my keepers, so that's not an issue for me, but I can see how it could be for others.
I also shoot raw+JPEG, and I still see one inconvenience to substantially "under-amplifying" in low light --- along with a potential solution, and one that is indeed already more or less offered by some cameras.
The problem is that if I used an ISO sensitivity setting that for some shots is well below what would be needed for "on-meter" exposure, the JPEG's and previews of the raw files will sometimes be way too dark, and then the problems start before I get to fine-tuning my keepers:
it becomes necessary to make rough level adjustments on every "under-amplified" image just to get a preview that allows me to decide which shots _are_ the keepers.
One solution for me involves:
a) A preview image (the OOC JPEG, or default raw->JPEG conversion) that has been amplified to roughly correct levels.
b) Raw files in low-light situations that have lower levels from "conservative amplification": that is, the raw level histogram has a significant gap at right.
Camera makers using almost "ISO-less" sensors could accommodate both goals by keeping the analog gain lowish, thus allowing an abundant safety margin against highlight clipping by over amplification in the raw file, but tagging the raw file with information about the intended exposure level, with this used in the in-camera JPEG conversion and in default conversion of the raw files by any software that knows about the camera (which includes Adobe DNG Convertor, Lightroom etc. once they are updated for each new model of camera.)
The good news is that many camera makers already do something like this
, so I think we might be over-thinking a situation that has already been addressed. I refer to cameras that use conservative analog gain at elevated ISO speed settings along with providing information about this that is used by raw convertors and in making in-camera JPEGs, thus offering both raw files with abundant highlight headroom and default JPEG versions with appropriate "viewable" brightness levels. These camera models are fairly easy to detect: they are the ones that offer substantial blown-highlight recovery from raw files, and for which the DxO measurement of "sensitivity" at elevated ISO settings is significantly less than the ISO sensitivity setting on the camera. That is, those cameras which some misguided followers of the over-broad ETTR doctrine ("the raw histogram should always be as far to the right as possible", even in low light/high ISO speed situations where read noise overwhelms ADC quantization noise) accuse of "cheating on" or "overstating" their ISO speed settings.