Steel road bikes offer a uniquely smooth, comfortable ride that many riders love for long days in the saddle. The material naturally absorbs road vibration better than aluminum, giving it a "supple" feel that's hard to replicate. Steel is also the most repairable frame material — a skilled frame builder can fix a bent or cracked tube, while carbon and aluminum typically require full replacement.
The trade-off is weight. Steel is the heaviest common frame material, so if you're chasing grams for racing or steep climbs, carbon is the better call. That said, modern steel alloys are significantly lighter than the heavy frames of decades past, so the gap isn't as dramatic as you might think.
Steel makes the most sense for randonneuring, custom builds, and riders who value longevity and ride character over outright performance. If you want a bike that lasts a lifetime and ages gracefully, steel is tough to beat.