There might be a good reason for this. Raster effects were already really good in newer games, and ray tracing could only improve on that high bar. It’s filling in details that are barely noticeable, but creap ever so slightly closer to photorealism.
Old games start from a low bar, so ray tracing has dramatic improvement.
A couple newer games have raytracing that genuinely adds detail but it’s pretty subtle and you have to look for it. Cyberpunk 2077 is a good example.
Portal and Minecraft are particularly good examples of raytracing because of how their sandbox aspects let you play with it.
There absolutely is a factor that modern graphics are so even without ray tracing is doesn’t add a whole lot. I still think Destiny 2 is one of the best looking games I’ve played and it uses fairly “old” graphics technology. The reason it looks good is their artists do a good job.