Some PS1 games look much better in emulators too, in much different ways. For example, sometimes they use textures that are a lot higher resolution than what usually gets expressed in screen space, causing the detail to be wasted and more aliasing. Higher resolution rendering makes these games look a lot better. For example, Chrono Cross.
This doesn't help the fundamental sub-pixel precision or affine interpolation issues though. There was an experimental emulator under developement that actually did somehow overcome some issues like this, probably with heuristics that track primitive data with the GTE calculations that produced it (and included more information). Not sure if that ever got released.