UE4 materials are very nice. It’s going to be even better when we get access to photoscanned stuff like http://www.quixel.se/dev/megascans
I think the bad materials you see are because people use bad textures to start with! Personally, I only use Arroway textures nowadays. They are awesome
Have you ever seen the map outpost-23 from the new unreal tournament? It’s looking dangerously real. Apply the same quality and level of details for archviz and it’s awesome.