I can understand not liking them in GTA3, but in Vice City they do far more than just adding motion blur :\ with them off, the streets are bland and the lighting is grey unless *directly* near a neon light but with them on the entire city takes on a neon glow at night, and during the day the sun warms the entire city with it's glow
plus, 60 FPS + motion blur = kickass unless you have a slow machine or are running in low res