Many newer games are designed to show off raytracing effects. Cyberpunk 2077 has lots of neon lights, shiny things, rain puddles, etc for light to bounce around, and raytracing makes it look a lot nicer than when the shadows are approximated in traditional ways. Minecraft ... ye gods. The videos I've seen look amazing. The other nice thing these cards have is the DLSS 2.0 tech, which is supposed to let it render at higher resolutions by _making things up_ (?) based on ... something buzzword-laden. The effect, though, is that you get similar or better quality at much higher framerates, because lossy techniques are still nice to look at.
"Need" is a strong word, but I'm sure someone will make a game where the shadows _matter_ for telling the story, or solving puzzles, or even just making the game world look more realistic and believable.