So there's this response to the usual complaints about the Wizards of the Coast editions of D&D that goes something like: "What are you guys complaining about? You've got your own games to play. Stop talking about how you don't like ours."
And that's a perfectly legitimate position. Personally, I see a lot of value in figuring out exactly what it is you don't like about a game, especially a game that can be easily compared to a game you do like, but within the internet community those discussions often wind into less useful complaints. It's a lot better to get some enthusiasm going about the game you do play than spend all your time grousing about the game that you don't.
But it's like this: Imagine that you know a guy. (Or a girl. Adjust the pronouns to taste. Works either way.) A guy you really, really like, and who likes you back. You start dating, and it's great. He gets you, you get him, and you spend a couple of really wonderful years together. Sure, some of the time things get frustrating, neither of you is perfect, but you're able to work past that. You start seeing a future together.
But then he changes. First a little, then more and more, until suddenly that thing that you had, that perfect something between you, is gone. You break up, and he moves on to some other tart, who's younger and richer and better looking. You find a new guy yourself (if we want to take this metaphor way too far, you clone your old boyfriend and download his old memories into the clone) but even if you're glad your old boyfriend is happy, it still hurts.
Now, I can't speak for everyone who plays an older version of D&D in preference to 4e. All I've got is my own experience, of being way into 3rd Edition with a major company supporting it and being part of the dominant gaming experience, and then trying to move on to 4e and finding out that it just wasn't for me, at least as a long-term, go-to kind of game. I'm happy with the D&D I have now -- both my beloved 3rd edition and my new old school flames. But that doesn't mean that it's not a little weird to have everyone playing and discussing and caring about something else.