Here’s a comparison between light radius in D2R legacy graphics vs D2R graphics. Notice how +light radius makes a big difference in legacy graphics while it makes basically no difference in D2R graphics (just a infinitesimally small increase on the very edge of the light). You can see negative light radius is working as intended in D2R graphics as well.
While I do greatly appreciate that the devs kept the same dark atmosphere it would be nice if Light Radius were as meaningful in D2R graphics as it is in original D2 graphics.