The Simpsons stopped being really funny when they stopped using the A plot B plot formula. Usually there was an A plot with the moral baggage, supported by a (usually waaaay funnier) B plot and they weaved in and out of each other.
Frank Grimes plot A / Bart owns a factory plot B.
Marge helps out at the church plot A / Homer finds his face on a Japanese soap package plot B.
NuSimpsons for the past 10 years or so usually does one plot in one straight line but it meanders so much if you watched the first third and the last third you would have no idea that the plots were connected. [/rant]. That's what happened to the Simps IMHO. Still watchable, but I miss the distinctive plot threads.