We all do it, myself included. We look at 'classic' games through nostalgic glasses, remembering the good times we had with games "back in the day". This GamersWithJobs story about gamer nostalgia hits the nail on the head--we're much more forgiving the first time we experience a new gameplay mechanic, and we (as gamers) expect to see constant refinement and improvement as we play new games.
Going back and playing Goldeneye or Half-Life now just wouldn't be as amazing an experience as it was when we first played. With a few notable exceptions, when I revisit my old favorites they don't seem as awesome I remember them being.
While I agree with the GamersWithJobs guys basic premise--older doesn't necessarily mean better--there are still lessons to be learned from classic games. The biggest problem many of today's games face is accessibility. While a few modern games do a decent job guiding you through the early portions of the game in an entertaining and still informative way, most just force you through a tedious tutorial level or worse; they toss you into the fray with no idea what to do. Making a gamer's first 10 minutes with your game tedious and un-fun is a sure-fire way to guaranty that they don't buy the sequel.