We're born, blessed by genetics with certain innate predispositions, and thrust into the circumstances of our lives, where nature and nurture conspire to make us who we ultimately become. Along the way we pick up interests; and if these survive the rigors of an ever-changing brain, they become lifelong passions. To the extent that these are programmed, our nostalgia isn't a bad thing - it's merely inevitable. Nostalgia, then, is what happens when we're lucky enough to accumulate interests and value them.
Our physical brains are still developing through young adulthood, with at least some of our personalities and preferences arising from this formative time. This makes my abiding love of old-school D&D a bit of biological programming. So? To wax metaphysical, I have friends who ask how I can value love when I think it's just (their word, not mine) a chemical process in our brains. To this I reply, so what? Love is wonderful no matter where it comes from, physical or otherwise, and I can value it on that basis. Love is what it is...
Ditto for gaming. Sure, if I'd been born in 2006 I might be playing 5e and listening to (I honestly don't know what kids are listening to now) the latest thing. Instead, I prepare my next adventure while listening to Ozzy era Black Sabbath. It doesn't matter that it's the byproduct of my raising. I like it. Sue me for having a happy life and valuing my personal experiences. It is what it is and I like it. Anyway, I'm hard pressed to devalue nostalgia when it's really just us liking the thing(s) we've become through living.
So much for nostalgia. Now let's play it forward. Modern gaming enthusiasts are also being programmed by nature and nurture. Sure, there are objective things we can say about 5e (quite a lot of them, obviously). But we can say the same about the OSR, and our personal preferences come from the same place(s) regardless. This ends nostalgia as a pejorative term. It does nothing to diminish the objective facts about what we like, especially since the next generation is building their own future nostalgia - and we should all be so lucky!