Well in the case of Doom: The Dark ages, it's not just about about fidelity but about scale and production. To make TDA's levels with the baked GI used in the previous game would have taken their artists considerably more time and resulted in a 2-3x growth in install size, all while providing lighting that is less dynamic. The only benefit would have been the ability to support a handful of GPUs slightly older than the listed minimum spec.

Ray tracing has real implications not just for the production pipeline, but the kind of environments designers can make for their games. You really only notice the benefits in games that are built from the ground up for it though. So far, most games with ray tracing have just tacked it on top of a game built for raster lighting, which means they are still built around those limitations.