I think the issue of the second image is what ever shortcut they have taken to achieve playable framerates is giving us an image that is too bright( as you have correctly identified) and the colour on the walls is too uniform as if being evenly lit.I am not saying that the first picture is right i think it is too dark but i think the second one is too bright. The light on the floor looks fine but the walls are too bright. That is the problem with RT, we are not talking about real light/walls/sand so how do we know how much light is enough?
I tried looking for some full raytraced scenes on art Station for comparison but my search ability is failing me