I can agree that autogenerated curve is OK for preview purposes. But it is bad and confusing as starting point for quality image editing. Autogenerated curve don't allow to use any normal raw adjustments at all:
It makes impossible to adjust real Exposure manually.
It makes impossible to adjust real White Balance manually or pick WB with Channel Mixer picker.
It require "Use in-camera White Balance" enabled, otherwise it will be a lot of crazy clipped saturated artifacts in highlights.
As for too dark images - "Brightness" is simply an Exposure adjustment. (Levels in Linear gamma)
It is possible to get the same nice looking image in single click if use proper fixed Base Curve from camera model and apply "Levels Auto Mode" for Lights only before that curve. Guess this could work in same automatic way to generate preview thumbnails:
One thing that i still can't understand is how to get original camera Base Curve? Currently i discover base curve presets for different cameras in darktable. Also i find similar Base Curves for different camera models in Iridient Developer and there is an option there to export them as curve preset files. Those precise and complex curves usually made by camera manufacturers based on each specific camera sensor model. Any idea if those Base Curves data reads directly from RAW files or collected in some external database?
If someone want to test and feel how to operate in "true raw way", here is my PLD example project.
For this PLD placeholder example you need this Fuji X-E4 RAW example:
https://www.dpreview.com/reviews/image- ... 1698e8.raf
For this example Raw settings set like this:

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