Futurama can get away with the wackiness and nonsensical plot turns because it's set in a time period where anything goes. That's how Futurama is and always was from Episode 1.
It's not the same with Simpsons, though. They've been doing wacky and retarded bullshit only since Episode 200, and it's as if it's not even the Simpsons anymore. Matt Groening even said in one of the Season 1 DVD commentaries that the Simpsons was designed to be a show, as crudely drawn as it may be, where there was only true-to-life events and plots, as if it weren't even a cartoon at all. Then these new writers jizzed all over it, put it on TV, and that's what the Simpsons currently is.
The Halloween episode was awful, and I'm seriously considering not watching the rest of the season.
This is just like the new Coke, only they aren't bringing back the classic.