A lot less work for developers, smaller game sizes, and map and game design no longer needing to be built around the onerous limitations of raster lighting and reflections.
Ray tracing is a bigger deal than most people realize. It feels like a gimmick because the games that support it today are still ultimately designed around rasterization.
Path-traced lighting in particular is a huge game changer, and means developers will no longer have to choose between rudimentary global dynamic lighting and very static and storage-intensive baked lighting. You can get the benefits of both without the drawbacks of either, assuming the hardware is up to snuff.