I think the best demo to make right now to help users understand the "why" of raytracing is to show the limitations of otherwise very impressive stand-ins for it in traditional rendering. So while screen-space reflections still look stunning, all it takes is obstruction from something in the foreground or tilting the player view downward too much to immediately lose the effect. When you realize how many angles we can't use it for at all, you notice that everywhere in normal games. We have very nice faked light-shaft effects, but you see how that falls apart next to totally dynamic casting/parrallel refraction through transmissives. While shadow-maps do a good job of giving the sense of dynamic shadows, the limitations in resolution, color, and contact properties are easy to see next to the real thing.
There's a reason something as visually "simple" as Minecraft is already a showcase, next to some of the best art in the industry. Raytracing and path-tracing bring the curiosity of virtual spaces back into focus more than anything this side of VR. We're moving on from impressively crafted dioramas to building totally dynamic spaces, with the properties of light "inherently" built into it. This isn't even all-or-nothing, and we're at the start of developing smarter ways to use the tools, and the tech behind it.