I used to be a rabid ST:tNG loyalist as far as #1 top-amazing-best sci-fi shows is concerned. Obviously, upon seeing Our Mrs Reynolds back on 10/4/02 my heart foresworn to Gene Roddenberry was torn from my chest and shoved down Joss's throat. Or maybe Joss was shoved down my throat- no matter- I was IN LOVE. And I think I understand why. Why I became so latched and so absorbed and so desperate for the next episode- Joss manages to uphold a suspension of disbelief.
I never really got into Buffy or Angel- I'll admit that the writing was witty and keen and a fun time for everyone, but I could never just... get into it. I believe, when I watch Firefly. I believe, because- (now, wait for it.) There are no aliens.
There is no reason we can't watch an episode or three or thirteen and say "Yes. This is where we will be in five hundred years. This is where humans will have progressed to. I could live here I could be this person. I could do this." Because there's no reason not to believe. There's nothing in Joss's writing or what exists in this world he shows us that we don't already have traces of in our own society. With all other sci-fi shows there is something paranormal or extraterrestrial that we have no proof of or links to here on Earth, and it keeps you from being able to relate. There's no way to say, as humans in 2005, "Oh sure! We'll be rubbing elbows with spotty brown humanoids with washboard foreheads in NO TIME!" ...No. Just no. This is where Roddenberry and Lucas and O'Bannon (Farscape) and Straczynski (Babylon 5) all failed to connect with their audiences: Relativity.
I'm just so impressed by Joss's ability to make it tangibly realistic. He wins a hundred cookies from me for that.