Just read the first post and browsed through the answers so forgive me if I repeat something.
I wouldn't say they don't make games like this anymore - back then Wing Commander was revolutionary, in terms of graphics, narration, music maybe and non-linear story. Nowadays this is pretty common. You might say everything has been done and you can't invent the wheel again. They still make very good games (Mass Effect and Fallout 3 pop to my mind) but they can't be revolutionary.
What striked me when I recently played WC1 was how bug-free the game was. Back when there wasn't internet, you couldn't ship a half-finished game and just send out patch after patch to improve it. If some company sold a buggy game, they would have a hard time selling their next games (think Outpost by Sierra). So instead they thoroughly tested their games and made sure there weren't any crucial bugs (then of course the hardware and so~~~are was much more simple back then). I don't think WC1 or WC2 ever crashed on me or contained any serious bugs, none I would be aware of at least.
Other than that, I think it's just nostalgia that makes us think that that kind of games isn't made anymore. And maybe the fact that with everyone owning a PC nowadays, you can sell much more trash without worrying about the return on investment.