The notion that games can't age is idiotic. We improve our art, refine our tech, and do better. When you take Sly Raccoon and do an HD re-release, and fix the 1st game's camera, you have improved it. Moreover, you should improve it, because we've discovered better ways of doing things and can improve it. To not do so would be to release an old game in a modern era, where its control scheme would be regarded as archaic and inferior - it would have aged poorly.
On the other hand, Super Mario World's controls and mechanics are every bit as tight now as they were in the 90s. We've not improved the technology and mechanics used in that genre to such a point that Mario World is not still crazy playable. It has aged well.
As mentioned elsewhere in this thread, System Shock is a stellar piece of early 90s cyberpunk, and an incredibly important game. If you play it these days and don't play Enhanced Edition, you're only hurting your own experience. The standard controls are (and always were) clunky and barely playable. Mouse-look, an innovation that didn't hit gaming until Future Shock in 1995, so massively improved PC controls that FPS games before it immediately feel dated, and adding it to System Shock immediately revolutionises the game. The fact that we didn't know better back then is literally the entire point.
As a guy with more consoles than is really sensible (stretching back to the early 80s) to deny that many retro games don't hold up to nostalgia, or that we've improved upon them since, is myopic.