I can see three serious problems with this:
1, The PSX and Saturn are fundamentally 2D in terms of rendering, therefore their emulators do not get any depth information about the polygons they draw and cannot place them in 3D space.
2, There is a lot of fake lighting in older games. Take Conkers’ Bad Fur Day for example. You see shadows, and they look nice. The emulator sees dark polygons. There is no light source the emulator can identify, even if it could somehow deduce that one should exist.
A common trick is to bake lighting into textures, and again the emulator has no information about where the lights are, or even whether the textures have lighting baked onto them.
3, Raytracing a scene involves more than what you can see directly. Everything a ray can hit, changes the final image in some way. The issue here is that if you cannot see something, the game probably won’t try to draw it, and the emulator cannot tell if it is supposed to be there.
For example: You confront Cyrano de Bergerac. You see the shadow of his oversized nose against a wall. He turns his back to you. The nose shadow disappears.
You might think this wouldn’t matter, and if you were rendering still images you would probably be right, most of the time. However, polygons will appear and disappear frequently, changing the lighting in subtle and not so subtle ways, in scenes where the lighting shouldn’t really change. My expectation is that this would be conspicuous enough to be annoying.