What impresses me most about graphics in any sense is design. Art. Without the design and the art you don't have anything to look at anyway.
Everything from textures, to geometry, shaders, IQ, and framerate merely exist to support the art. Something that a lot of game creators struggling to replicate reality seem to forget, making bland photorealistic games that look ugly in just a few years, when technology improves again.
With the right art, any piece of hardware can produce a pleasing image. In fact, at this point, the hardware for polygon based visuals is so advanced that the main benefit from more powerful hardware is to art styles that are generally realistic - and tipped relatively far towards the "photographic" end of the scale. The other current advantage is games with large and open world designs, since scale does impact granular quality.
Bloodborne for example, looks better than Dark Souls 2 PC largely because it has far, far superior art and visual direction.Though in a purely technical sense, it does seem to use a lighting system more advanced than DS2 (more like the lighting in the DS2 vertical slice).
If it's getting harder to wow and boggle people with raw hardware, it's because those naughty diminishing returns mean that people are used to decent IQ, higher resolutions, 60fps (on PC), and good textures. As has been said many times the dawn of accelerated 3D visuals can't happen twice. The biggest wow moment was at the beginning, and each subsequent wow has been smaller.
