Light radius would be useful if it actually increased your light radius in D2R graphics, it makes a notable difference in legacy graphics but D2R it’s an infinitesimally small difference.
I saw a cool site awhile back that lets you compare images with a slider, so I took multiple screenshots that compare various amounts of light radius (base amount, +5 which is max, and even negative amounts) that makes it very easy to see the difference and how useless it is in D2R.