Mostly because it's quality is not acceptable, it's worse than AT Games efforts.
PS1 also doesn't have that much of a nostalgia factor. It was my first self bought console, yet I don't have great memories of the 3D games on it apart from MGS and Wipeout 2097. A PS2 mini would do a lot better. I still have one hooked up yet it's a hassle with them old inputs, wired controllers and top loading discs.