Back on topic, I feel the thing that makes DF so good is that it harks back to the golden years of 1985-1995 when computer games had to be creative to be truly successful. After that, creativity amongst game designers seems to have almost died out, at least in commercial ventures.
I definitely agree, DF makes me think of the games made during that time.. the thing about games from back then is that while the presentation and UI weren't as good as they are today, the way that the games were designed made it feasible to have some very innovative, imaginative, and complex systems in the games.
For instance, if a gaming studio of today made a tile-based Ultima-style RPG game with $4 million today, I personally believe that they could make a game which is 5x better than the first-person shooter or RTS eye candy-fest kinds of games that they now make.
A large part of what made games good back then is that the framework that the games were laid within was pretty simple, thereby making it possible to make the gameplay and gameworld quite complex. Nowadays, they make the framework complex, and they end up only being able to make the world and gameplay simple.
Nowadays they're building games with their materials basically being whole rooms of houses, whereas back in the day they were using nails, bricks, boards, and glue. A kind of stilted analogy, but when you're building with only rooms, you're not going to make anything new, just the same houses as before.
Part of the reason that DF is what it is is that it's made with glue, boards, bricks and so on. Hell, I think Toady even mixes the glue himself.
The only games worth playing today I think are those in which the designers hearken back to the same kind of mindset that people who made games in the 80s-90s were in. It could just be nostalgia, but personally I think that the craft of game-making has degenerated to some degree (could Microsoft be to blame for this to some large degree?); but with indie games like DF, Aquaria, and many others coming out of the woodwork today, I think we'll be in good shape again soon.
Ramble, ramble, ramble.. hell it's more fun to talk about games sometimes today than it is to play them.