I'm talking about Futurama here because I enjoy it (though not to the nearly unhealthy degree which many of my friends do), but I think bringing it back is going to disappoint people. Whenever audience outcry prompts the comeback of a canceled TV show (and it's a very rare occurrence), the new episodes compare poorly to the originals. Twin Peaks is the best example I can think of, but The Family Guy is probably more familiar to you.
Many of my friends were ecstatic when The Family Guy's resurrection was announced, but when the new episodes premiered they griped about the loss of the show's satiric edge. American Dad has the same problem: it looks and feels like a Seth MacFarlane production, and yet the humor tastes watered down. This is not a coincidence. We're talking network TV here. When The Family Guy came back, its creators were at the mercy of Fox -- not the other way around.
The Family Guy was smart and edgy and incredibly offensive to a lot of people. Futurama is also smart and edgy and incredibly offensive to a lot of people. The hiatus gave Seth MacFarlane and his cowriters time to mature (or at least change) their sensibilities. More importantly, Fox had time to scrutinize The Family Guy, figure out how and why it worked, and how it could be made to work better. They didn't say "stop making fun of Republicans" or anything like that, but I'm sure there's an unofficial list of "Topics the Show Can't Touch" which was created after The Family Guy's initial run. It's a Family Guy-specific list that doesn't apply to any other show. There's probably also an official list of "Things That Got a Good Audience Response and Which Should Happen on the Show More Often." This is the way these things are done.
Fox's goal is not to please the purists, but to grab as many viewers as they can. If making a show accessible means watering it down to just above the point where old fans get bored, that's what they'll do. The revival of a once-canceled show gives them an easy opportunity to throw their editorial weight around. The Family Guy's creators had control over the show while it was running, but Fox took the reigns after it got canceled. It doesn't matter that Fox came crawling back, they still had all the cards (and the reigns, I guess). Futurama, if it comes back to Fox (probably if it comes back to anywhere), will have the same problem.