The writing staff has changed a lot since the early days, and it’s hardly Fox’s fault that the likes of Conan O’Brien and the legendary John Swartzwelder have moved on. There’re still high quality names in the bunch too, with Carolyn Omine responsible for modern day greats like Looking For Mr Goodbart and Halloween Of Horror.
The problem isn’t necessarily the quality of the writing staff (not as far as you can blame Fox), but the sensibilities of it. There are two types of jokes modern day writers use a lot which so rarely land, yet they don’t take the hint.
These are jokes written for other Hollywood insiders, and meta references.
Both are the symptom of career writers not understanding The Simpsons.
The Hollywood insiders jokes are the ones where someone, usually Homer, says something or reacts to something as if they’ve spent their career in the biz. Technically, Homer does have some experience, but that’s never been part of his character. It’s jokes like Jesus not being that funny, despite having a twelve man staff.
The second issue are too many throwback jokes. Referencing Sideshow Bob’s rake nemesis can be funny if earned, but too often they feel like an empty reminder of what once was.