When you're thinking of older games, you're thinking about every game that's come out before a few years ago. That's a much bigger library than all the games that came out after your cutoff point, and, as a result, your memory has more more to cherry-pick examples of great games from. Therefore, an older player will have many more old games than new ones that he has fond memories of.
Time distortion is another important factor. Whether a game was released in 1999 or 2000 is not as important as distinguishing between games that came out this year and games that will come out next year. You'll see the same things in movies - it's much easier to name three movies that came out last year than it is to name three movies that came out in the whole decade of the 50's - and books (of which old ones are commonly lumped into centuries.) The huge relative size difference between the past releases and the present releases mean that the vast majority of the best material will always be in the distant past (except for very recent mediums.)
Very few people play the "average game" from a decade ago. They play the ones they still hear about, or the ones that they remember loving. The mere fact that you can find any significant amount of information about a given old game is a testament to its influence, and usually to its quality. New games are valued by their pre-release hype, their reviews, and how pretty they look on the shelf. They're much more likely to be talked about because they're new, not because they're good.
Games are actually slowly improving, IMHO. As new things are tried, game developers see what works and what doesn't work (though it is mostly mindlessly following a lot of fads like regenerating health, the current genre of the day, scores and life systems in earlier games, RPG elements today, free-to-play microtransaction models - a lot of things). But cheap deaths, completely faceless characters, mind-numbing difficulty caused by stupid game design, and aimlessly wandering about to try to figure out what the designers want you to do next are examples of old-school gaming staples that are all on the wane. I can't think of anyone unhappy to see them go.