It's allways newer games will have better graphics, but gameplay and graphics are different thing. Most of the 70's 80's games were crap...But so were 90's too. I was allways very selective about games I played, and still am.
If you think what are your favourite games, you do think only the best games of the era, not the worst. Playability at best 80's games is still quite awesome...It actually might be due to the fact that there wasn't so much graphics to program into a game...So you had to concentrate on making gameplay challenging. When Jarvis was making Robotron, he just played the game several months making small improvements on the way. Also 2D environment has some informational advantage over 3D, you see all enemy and bullets at once(robotron vs doom).
Another example of 2d being better is Trackfl vs 88games longjump. At TF you get more accurate info regarding how close you are to the line.
One of the very best alltime 3d games is from 80's. Starwars the videogame...Hard gameplay, and think about trench and towers, you see through walls because game is vector based...using different graphics, that would be hard to achieve. And I think that the game looks as cool as a game ever could...
There are good games at all times, but I think nostalgy is not only factor that makes me like 80's games. I might be 99% biased though
Nowadays there is some retro movement at games. Yet generally games are moving towards looking more and more real-world, and sounding...which is in a way cool too. I need my daily fix of bleeps and zaps though.