Let me begin by saying that I generally have little time for nostalgia in general. I've revisited some of my favorite television series from my youth, and realized that not only are they disappointing now, but I'm not real sure what I saw in them back then that made me enjoy them so much. Ditto video games. Ditto some music. Ditto some books I've read. So bear that in mind as you read on.
The following represents one grognard's opinion. It may provoke debate, which is perfectly fine.
I'm an old gamer. I'm not too terribly many years away from being eligible for an AARP card. I bought my first wargame, Avalon Hill's The Russian Campaign when I was 12. I bought my first RPG, the Traveller Little Black Book boxed set, at age 14. Both of those events are pushing 30-35 years ago. Back in those days I ran and played in a lot of Traveller, some of SPI's short-lived but excellent hard sci-fiRPG Universe, D&D (starting with the red box Basic Set, moving on to the Blue Box Expert set, and then on to First Edition AD&D). Later on I included things like Boot Hill, Tunnels and Trolls, Gamma World.
I don't play any of those games now and there's a reason for that. The art of game design has moved on past most of those old games. There are still some gems. I think Classic Traveller holds up reasonably well for its age, though I think the 1950's Golden Age of SciFi tropes and setting common to all versions of Traveller (including Mongoose's version), were actually tired 20 years ago at this point. I think Call of Cthulhu holds up remarkably well for the genre it represents, though I'm grateful Delta Green is there to remind people that present day Call of Cthulhu can be as good or better than the 1920's pulp setting Chaosium was so eager to detail. The truth is I was tired of 1st Ed AD&D and its progenitors before the Reagan Administration was over. I skipped 2nd Ed entirely (too similar to its predecessor), and really didn't pick up another version of D&D until 3rd Edition.
The biggest reason for this is that D&D and 1st Ed AD&D, boiled down to its nuts and bolts, were too table dependent (fuck Thack-Zero and the horse it rode in on), and frankly, for a newbie player, gave absolutely nothing to hang their hat on in terms of character design compared to most of its contemporaries, let alone the legion of designs that have come since. All you had were six abstract numbers. Comparing this to Call of Cthulhu, with its large number of occupations and skills, or Traveller and its prior career generation system, character design in pre-3rd Ed D&D seemed wonderfully quaint back in the early 1980's, let alone 20 years later when the rest of the world had pretty much left AD&D in the dust in terms of design.
This is kind of the RPG equivalent of pretending that wargame design peaked with Chess, or that first-person shooters never got better than classic Doom. While there's nothing wrong with admiring these games, or even playing them (I still play Call of Cthulhu, and have a near complete set of Classic Traveller books, including third party stuff), I would hardly want to go back to playing nothing but them.
I say this because in recent years, I've been somewhat amused by the Old School movement. Effectively it consists of using the 3rd Edition OGL to basically reconstruct 1st Ed D&D/AD&D. There are a number of systems doing this. Some of them are skewing so close to the style, design, layout, and text of the 1st Ed AD&D/Basic D&D that they might as well have taken the 1st Ed DMG, Player's Handbook, and Monster Manual removed the cover art, and just put a yellow-wrap cover on it like the old generic food labels of the 1980's.
Now some of the games are incorporating other innovations. I for one am rather impressed by Old School Hack, which ties together some of the basic D&D tropes with some more modern design concepts. It's not likely I'd ever play it, but I'll give it, and some of the others, credit for not just trying to recreate a design that had ceased to be interesting before the fall of the Berlin Wall.
However, I have to say I have no idea why somebody would go all the way back to something like OSRIC, which painstakingly reconstructs 1st Ed AD&D out of 3rd Ed, and tries to pretend that 30 years of design, and more importantly, innovation never happened. I've been there. I've played all the 1st Edition AD&D I ever want to play, and frankly, I didn't enjoy it that much after a while back then.