I agree 100%. They definitely overdid it. The only light source in the entire orbiter is now from the two windows, it's as if the indoor lights are completely non-functional. While the new shadows are technically more impressive, they're not visually more impressive. Everything is too dark.
Some examples from my humble Orbiter:
The spotlight in the center of the arsenal is completely gone. This was there so that you could get accurate arsenal previews that aren't in the dark, it's just gone now.
In deleting all the other lights, they forgot about the Railjack docked above. It's in total darkness now, and if it wasn't for the Tempestarii skin it would be invisible.
Worst of all, my Plains of Eidolon vignette that I paid platinum for had its light source and sun shafts deleted. Which ruins the entire look.
I've gone through the Drifter Camp as well and different planets and the light is always about the same; too dark because of the absence of indoor lights. I run Warframe with everything on High, by the way. I've also suddenly dropped about 30 frames with this lighting update.
DE, please revert this until you've gone through and added indoor light sources and optimized it.