Blocky and sloppy aren't necessarily one in the same, though. I mean, HL2 is at times as minimalist as you can go and remains interesting through the entire scene's composition (plus the gameplay they build it for).
Really, as brushes get sort of pushed to the backburner, they should be the last thing that's sloppy anymore, with prop placement/detailing, scene framing, lighting, etc. being the potential visual snags.