Family Guy was pretty popular during its first run, and I recall it being super-hyped before it aired (didn't it premiere right before the Super Bowl in 1997 or so?).
And I can't think of many people who didn't become famous until after they died that also didn't live 100+ years ago when we didn't have much in the way of mass media to keep people informed of the latest art/music/literature/etc.
I get what you're saying, and yes, it's possible (even likely) that Arrested Development would have gotten worse over time. It certainly seems to be more common than not. However, no matter how bad it would have become, and even if the upcoming season flops, it doesn't take away from the greatness of the first 3 seasons. And those 3 seasons are all better than The Office's best seasons, IMO.
Again, look at The Simpsons...everyone knows it's sucked for many years now, but still recognizes how great the early years were.