I play a lot of new releases, because it's kind of hard to be a critic if you're stuck in the past without a funny persona. However, I have these phases where I go through several games on an older system. For instance, when I saw the Game Gear VC library on the 3DS was starting to look pretty good, I was like "Yes. I need to play Game Gear games, now." I played the Shining Force game, Crystal Warrior and something I forgot the title of... Wait, Defenders of Oasis! That's the one. Good times.
Switching between eras can result in small shocks (wait, did the NES really only allow this many different colours on screen!?), but I've come to see those as part of the fun. They're a good reminder of how much progress videogames have made, sometimes in less than a decade!
Some jumps can have weird side effects, by the way. I played several Playstation 2 games before playing and reviewing Xenoblade Chronicles. While many critics were complaining about the textures and how much playing a Wii game sucks, I was just constantly amazed by the environments. (I did have a PS3 and Xbox 360 at that time, but I spend a lot of time reviewing handheld games that year, so... yeah, I may had kind of forgotten what many people considered normal.)